iOS 頁面?zhèn)髦抵嗌?？你真的了解嗎?/h2>

iOS開發(fā)中，頁面?zhèn)髦凳呛艹Ｒ姷?，但是頁面?zhèn)髦的憔烤怪蓝嗌倌兀抗P者這篇文章就是給大家介紹一下頁面?zhèn)髦档木唧w方式，有不足之處，歡迎大家指正，希望能和大家共同進(jìn)步。說明一下：這里所說的正向、反向傳值是指相關(guān)聯(lián)的兩個(gè)頁面間的傳值。

目前我所了解和掌握的傳值方式有：屬性傳值、代理傳值、Block傳值、KVO傳值、通知傳值、單例傳值、KVC傳值。

下面我們來一一看下它們究竟是怎樣進(jìn)行操作和傳值的呢？

假設(shè)我們現(xiàn)在有控制器（頁面）A和控制器（頁面）B，A->push->B，即A是B的上一個(gè)頁面（控制器）。

  1. 屬性傳值
    用法：正向傳值
    需求：當(dāng)A-push到B時(shí)，B中有一個(gè)Label需要顯示從A中的一個(gè)TextField輸入的內(nèi)容，這時(shí)我們需要用到正向傳值。

    A控制器.m文件：

     #import "A_ViewController.h"
 #import "B_ViewController.h"
 
 @interface A_ViewController ()
 
 @property (nonatomic, strong) UITextField *aTextField;
 
 @end
 
 @implementation A_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     
     self.title = @"A";
     self.view.backgroundColor = [UIColor whiteColor];
     self.aTextField = [[UITextField alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];
    
     self.aTextField.layer.borderColor = [UIColor grayColor].CGColor;
     self.aTextField.layer.borderWidth = 1;
     [self.view addSubview:self.aTextField];
     
     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
     button.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 280, 100, 30);
     [button setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
     [button setTitle:@"傳到B" forState:UIControlStateNormal];
     [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:button];
     
 }
 
 - (void)buttonAction:(UIButton *)sender {
 
     /**
      什么時(shí)候可以用 屬性 傳值
      
      A 傳到 B，正向傳值
      
      B 在 A頁面 提前初始化
      
      **/
     
     B_ViewController *bViewController = [[B_ViewController alloc] init];
     bViewController.string = self.aTextField.text;
     [self.navigationController pushViewController:bViewController animated:YES];
     
 }

 @end

    B控制器.h文件：

     #import <UIKit/UIKit.h>
 
 @interface B_ViewController : UIViewController
 
 @property (nonatomic, copy) NSString *string;
 
 @end

    B控制器.m文件：

     #import "B_ViewController.h"

 @interface B_ViewController ()
 
 @end
 
 @implementation B_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     
     self.title = @"B";
     self.view.backgroundColor = [UIColor whiteColor];
     
     self.view.backgroundColor = [UIColor whiteColor];
     UILabel *bLabel = [[UILabel alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];
     
     bLabel.layer.borderColor = [UIColor grayColor].CGColor;
     bLabel.layer.borderWidth = 1;
     [self.view addSubview:bLabel];
     
     bLabel.text = self.string;
 }

 @end

  2. 代理傳值
    用法：反向傳值：
    需求：A-push到B，當(dāng)B消失的時(shí)候，A中有一個(gè)Label需要顯示從B中的一個(gè)TextField輸入的內(nèi)容，這時(shí)我們需要用到反向傳值。

    A控制器.m文件：

     #import "A_ViewController.h"
 #import "B_ViewController.h"
 
 @interface A_ViewController () <BToADelegate>
 
 @property (nonatomic, strong) UILabel *aLabel;
 
 @end
 
 @implementation A_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     
     self.title = @"A";
     self.view.backgroundColor = [UIColor whiteColor];
     self.aLabel = [[UILabel alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];
     
     self.aLabel.layer.borderColor = [UIColor grayColor].CGColor;
     self.aLabel.layer.borderWidth = 1;
     [self.view addSubview:self.aLabel];
     
     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
     button.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 280, 100, 30);
     [button setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
     [button setTitle:@"push到B" forState:UIControlStateNormal];
     [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:button];
     
 }
 
 -(void)buttonAction:(UIButton *)sender {
    
     B_ViewController *bViewController = [[B_ViewController alloc] init];
     //設(shè)置代理
     bViewController.delegate = self;
     [self.navigationController pushViewController:bViewController animated:YES];
 }
 
 /**
  什么時(shí)候可以用 代理 傳值
  
  B 傳到 A，反向傳值
  
  B 在 A頁面 初始化
  
  設(shè)置A為B的代理
  
  執(zhí)行代理方法
  
  **/
 - (void)transferString:(NSString *)string {
     
     self.aLabel.text = string;
 }
 
 @end

    B控制器.h文件：

     #import <UIKit/UIKit.h>
 
 // 聲明代理
 @protocol BToADelegate <NSObject>
 
 // 代理方法
 - (void)transferString:(NSString *)string;
 
 @end
 
 @interface B_ViewController : UIViewController
 
 // 代理屬性
 @property (nonatomic, weak) id<BToADelegate> delegate;
 
 @end

    B控制器.m文件：

     #import "B_ViewController.h"
 
 @interface B_ViewController ()
 
 @property (nonatomic, strong) UITextField *bTextField;;
 
 @end
 
 @implementation B_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     
     self.title = @"B";
     self.view.backgroundColor = [UIColor whiteColor];
     
     self.view.backgroundColor = [UIColor whiteColor];
     self.bTextField = [[UITextField alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];
     
     self.bTextField.layer.borderColor = [UIColor grayColor].CGColor;
     self.bTextField.layer.borderWidth = 1;
     [self.view addSubview:self.bTextField];
     
     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
     button.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 280, 100, 30);
     [button setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
     [button setTitle:@"傳值A(chǔ)" forState:UIControlStateNormal];
     [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:button];
     
 }
 
 - (void)buttonAction:(UIButton *)sender {
     
     // 判斷有沒有代理以及代理是否響應(yīng)代理方法
     if (self.delegate && [self.delegate respondsToSelector:@selector(transferString:)]) {
         [self.delegate transferString:self.bTextField.text];
     }
     
     [self.navigationController popToRootViewControllerAnimated:YES];
 }
 
 @end

  3. Block傳值
    用法：反向傳值：
    需求：A-push到B，當(dāng)B消失的時(shí)候，A中有一個(gè)Label需要顯示從B中的一個(gè)TextField輸入的內(nèi)容，這時(shí)我們需要用到反向傳值。

    A控制器.m文件：

     #import "A_ViewController.h"
 #import "B_ViewController.h"
 
 @interface A_ViewController ()
 
 @property (nonatomic ,strong) UILabel *aLabel;
 
 @end
 
 @implementation A_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     
     self.title = @"A";
     self.view.backgroundColor = [UIColor whiteColor];
     self.aLabel = [[UILabel alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];
     
     self.aLabel.layer.borderColor = [UIColor grayColor].CGColor;
     self.aLabel.layer.borderWidth = 1;
     [self.view addSubview:self.aLabel];
     
     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
     button.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 280, 100, 30);
     [button setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
     [button setTitle:@"push到B" forState:UIControlStateNormal];
     [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:button];
     
 }
 
 - (void)buttonAction:(UIButton *)sender {
 
     B_ViewController *bViewController = [[B_ViewController alloc] init];
 
     __weak __typeof(self) weakSelf = self;
     // block 回調(diào)接收
     [bViewController setBlock:^(NSString *string){
         weakSelf.aLabel.text = string;
     }];
     
     [self.navigationController pushViewController:bViewController animated:YES];
 }

    B控制器.h文件：

     #import <UIKit/UIKit.h>
 
 // 定義一個(gè)block
 typedef void(^BToAblock)(NSString *string);
 
 @interface B_ViewController : UIViewController
 
 // block 屬性
 @property (nonatomic, copy)BToAblock block;
 
 @end

    B控制器.m文件：

     #import "B_ViewController.h"
 
 @interface B_ViewController ()
 
 @property (nonatomic, strong) UITextField *bTextField;
 
 @end
 
 @implementation B_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     
     self.title = @"B";
     self.view.backgroundColor = [UIColor whiteColor];
     
     self.view.backgroundColor = [UIColor whiteColor];
     self.bTextField = [[UITextField alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];
     
     self.bTextField.layer.borderColor = [UIColor grayColor].CGColor;
     self.bTextField.layer.borderWidth = 1;
     [self.view addSubview:self.bTextField];
     
     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
     button.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 280, 100, 30);
     [button setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
     [button setTitle:@"傳值A(chǔ)" forState:UIControlStateNormal];
     [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:button];
 
 }
 
 - (void)buttonAction:(UIButton *)sender {
     /**
      Blcok 傳值
         
      反向傳值
      
      B 傳到 A
      */
     _block(self.bTextField.text);
     [self.navigationController popToRootViewControllerAnimated:YES];
 }
 
 @end

  4. KVO傳值
    用法：反向傳值：
    需求：A-push到B，當(dāng)B消失的時(shí)候，A中有一個(gè)Label需要顯示從B中的一個(gè)TextField輸入的內(nèi)容，這時(shí)我們需要用到反向傳值。

    A控制器.m文件：

     #import "A_ViewController.h"
 #import "B_ViewController.h"
 
 @interface A_ViewController ()
 
 @property (nonatomic, strong) UILabel *aLabel;
 @property (nonatomic, strong) B_ViewController *bViewController;
 
 @end
 
 @implementation A_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     
     self.title = @"A";
     self.view.backgroundColor = [UIColor whiteColor];
     self.aLabel = [[UILabel alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];
     
     self.aLabel.layer.borderColor = [UIColor grayColor].CGColor;
     self.aLabel.layer.borderWidth = 1;
     [self.view addSubview:self.aLabel];
     
     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
     button.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 280, 100, 30);
     [button setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
     [button setTitle:@"push到B" forState:UIControlStateNormal];
     [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:button];
     
     /**
      KVO 創(chuàng)建 三步一定要寫
         1. 注冊觀察者
         2. KVO的回調(diào)
         3. 移除觀察者
      
      */
     
     // B 傳到 A ，反向傳值
     //注冊觀察者，注意：觀察者的注冊和移除要對應(yīng)，如果移除時(shí)發(fā)現(xiàn)沒有注冊觀察者，程序會(huì)crash
      self.bViewController = [[B_ViewController alloc] init];
     [self.bViewController addObserver:self forKeyPath:@"string" options:NSKeyValueObservingOptionNew context:nil];
 }
 
 - (void)buttonAction:(UIButton *)sender {
     
     [self.navigationController pushViewController:self.bViewController animated:YES];
     
 }
 
 // KVO的回調(diào)
 - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context {
     
     if ([keyPath isEqualToString:@"string"]) {
         self.aLabel.text = self.bViewController.string;
     }
     
 }
 // KVO 的移除方式  （和通知一樣要移除）
 - (void)dealloc {
     
     [self.bViewController removeObserver:self forKeyPath:@"string"];
 }
 
 @end

    B控制器.h文件：

     #import <UIKit/UIKit.h>
 
 @interface B_ViewController : UIViewController
 
 @property (nonatomic, copy) NSString *string;
 
 @end

    B控制器.m文件：

     #import "B_ViewController.h"
 
 @interface B_ViewController ()
 
 @property (nonatomic, strong) UITextField *bTextField;
 
 @end
 
 @implementation B_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     
     self.title = @"B";
     self.view.backgroundColor = [UIColor whiteColor];
     
     self.view.backgroundColor = [UIColor whiteColor];
     self.bTextField = [[UITextField alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];
     
     self.bTextField.layer.borderColor = [UIColor grayColor].CGColor;
     self.bTextField.layer.borderWidth = 1;
     [self.view addSubview:self.bTextField];
     
     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
     button.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 280, 100, 30);
     [button setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
     [button setTitle:@"傳值A(chǔ)" forState:UIControlStateNormal];
     [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:button];
     
 }
 
 - (void)buttonAction:(UIButton *)sender {
     // KVO
     // 把self.bTextfield.text 賦值給當(dāng)前屬性
     // 在A中 監(jiān)聽 當(dāng)前屬性
     self.string = self.bTextField.text;
     
     [self.navigationController popToRootViewControllerAnimated:YES];
 }
 
 @end

  5. 通知傳值
    用法：正向傳值
    需求：當(dāng)A-push到B時(shí)，B中有一個(gè)Label需要顯示從A中的一個(gè)TextField輸入的內(nèi)容，這時(shí)我們需要用到正向傳值。

    用法：反向傳值：
    需求：A-push到B，當(dāng)B消失的時(shí)候，A中有一個(gè)Label需要顯示從B中的一個(gè)TextField輸入的內(nèi)容，這時(shí)我們需要用到反向傳值。

    我們在此將兩種傳值情況寫到一個(gè)Demo中，所以將上述Label換為Textfield即可，如下：

    A控制器.m文件：

     #import "A_ViewController.h"
 #import "B_ViewController.h"
 
 @interface A_ViewController ()
 
 @property (nonatomic, strong) UITextField *aTextField;
 
 @end
 
 @implementation A_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     
     self.title = @"A";
     self.view.backgroundColor = [UIColor whiteColor];
     self.aTextField = [[UITextField alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];

     self.aTextField.layer.borderColor = [UIColor grayColor].CGColor;
     self.aTextField.layer.borderWidth = 1;
     [self.view addSubview:self.aTextField];
     
     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
     button.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 280, 100, 30);
     [button setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
     [button setTitle:@"傳到B" forState:UIControlStateNormal];
     [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:button];
     
     // 接收通知
     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(tzAction:) name:@"B2A" object:nil];
 }
 
 - (void)buttonAction:(UIButton *)sender {
 
     // 通知傳值 一般是用于回傳
     
     // 現(xiàn)在是 A傳到B，正向傳值
     
     // 發(fā)送通知的方法 要寫在執(zhí)行方法里面
     
     B_ViewController *bViewController = [[B_ViewController alloc] init];
     
     [[NSNotificationCenter defaultCenter] postNotificationName:@"A2B" object:nil userInfo:@{@"key":self.aTextField.text}];
     
     [self.navigationController pushViewController:bViewController animated:YES];
     
 }
 
 // 回調(diào)通知
 - (void)tzAction:(NSNotification *)sender {
     
     self.aTextField.text = sender.userInfo[@"key"];
 }
 
 // 移除通知
 - (void)dealloc {
     
     [[NSNotificationCenter defaultCenter] removeObserver:self];
 }
 
 @end

    B控制器.m文件：

     #import "B_ViewController.h"
 
 @interface B_ViewController ()
 
 @property (nonatomic, strong) UITextField *bTextField;
 
 @end
 
 @implementation B_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     
     self.title = @"B";
     self.view.backgroundColor = [UIColor whiteColor];
     
     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
     button.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 280, 100, 30);
     [button setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
     [button setTitle:@"傳值A(chǔ)" forState:UIControlStateNormal];
     [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:button];
 }
 
 //如果是從A傳到B的話,B.m里要?jiǎng)?chuàng)建一個(gè)init方法,在里面寫監(jiān)聽并在里面創(chuàng)建接收容器才能成功(因?yàn)槌绦蛳葓?zhí)行init方法再到viewDidLoad方法,當(dāng)傳值過去時(shí)在init就開始監(jiān)聽,如果這里沒有創(chuàng)建textField接收,那就傳不過去了,所以要在init里同時(shí)創(chuàng)建接收器(生命周期的問題));
 -(instancetype)init
 {
     if (self = [super init]) {

         [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(tzAction:) name:@"A2B" object:nil];
         
         self.bTextField = [[UITextField alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];
        
         self.bTextField.layer.borderColor = [UIColor grayColor].CGColor;
         self.bTextField.layer.borderWidth = 1;
         [self.view addSubview:self.bTextField];
 
     }
 
     return self;
 }
 
 //接收通知
 - (void)tzAction:(NSNotification *)sender {
     
     self.bTextField.text = sender.userInfo[@"key"];
     
 }
 
 // 移除通知
 - (void)dealloc  {
     
     // 移除所有
     [[NSNotificationCenter defaultCenter] removeObserver:self];
     
     // 移除某個(gè)
     // [[NSNotificationCenter defaultCenter] removeObserver:self name:@"tz" object:nil];
 }
 
 //發(fā)送通知
 - (void)buttonAction:(UIButton *)sender {
     // B傳到A，反向傳值
     [[NSNotificationCenter defaultCenter] postNotificationName:@"B2A" object:nil userInfo:@{@"key":self.bTextField.text}];
     
     [self.navigationController popToRootViewControllerAnimated:YES];
     
 }
 
 @end

  6. 單例傳值
    用法：正向傳值
    需求：當(dāng)A-push到B時(shí)，B中有一個(gè)Label需要顯示從A中的一個(gè)TextField輸入的內(nèi)容，這時(shí)我們需要用到正向傳值。

    用法：反向傳值：
    需求：A-push到B，當(dāng)B消失的時(shí)候，A中有一個(gè)Label需要顯示從B中的一個(gè)TextField輸入的內(nèi)容，這時(shí)我們需要用到反向傳值。

    我們在此將兩種傳值情況寫到一個(gè)Demo中，所以將上述Label換為Textfield即可，如下：

    A控制器.m文件：

     #import "A_ViewController.h"
 #import "B_ViewController.h"
 #import "DanLi.h"
 
 @interface A_ViewController ()
 
 @property (nonatomic, strong) UITextField *aTextField;
 
 @end
 
 @implementation A_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     // Do any additional setup after loading the view.
     
     self.title = @"A";
     self.view.backgroundColor = [UIColor whiteColor];
     self.aTextField = [[UITextField alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];
     
     self.aTextField.layer.borderColor = [UIColor grayColor].CGColor;
     self.aTextField.layer.borderWidth = 1;
     [self.view addSubview:self.aTextField];
     
     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
     button.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 280, 100, 30);
     [button setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
     [button setTitle:@"傳到B" forState:UIControlStateNormal];
     [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:button];
     
 }
 
 - (void)viewWillAppear:(BOOL)animated
 {
     // 單例 傳值 B傳到A （可以雙向傳值）
     DanLi *danli = [[DanLi alloc] init];
     
     self.aTextField.text = danli.value;
 }
 
 - (void)buttonAction:(UIButton *)sender {
     
     // 單例 傳值 A傳到B （可以雙向傳值）
     DanLi *danli = [DanLi sharedDanLi];
     danli.value = self.aTextField.text;
  
     B_ViewController *bViewController = [[B_ViewController alloc] init];
 
     [self.navigationController pushViewController:bViewController animated:YES];
     
 }

    B控制器.m文件：

     #import "B_ViewController.h"
 #import "DanLi.h"
 
 @interface B_ViewController ()
 
 @property (nonatomic, strong) UITextField *bTextField;
 
 @end
 
 @implementation B_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     
     self.title = @"B";
     self.view.backgroundColor = [UIColor whiteColor];
     
     self.view.backgroundColor = [UIColor whiteColor];
     self.bTextField = [[UITextField alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];
     
     self.bTextField.layer.borderColor = [UIColor grayColor].CGColor;
     self.bTextField.layer.borderWidth = 1;
     [self.view addSubview:self.bTextField];
     
     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
     button.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 280, 100, 30);
     [button setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
     [button setTitle:@"傳值A(chǔ)" forState:UIControlStateNormal];
     [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:button];
     
     self.bTextField.text = [DanLi sharedDanLi].value;
 }
 
 - (void)buttonAction:(UIButton *)sender {
     //B傳給A
     [DanLi sharedDanLi].value = self.bTextField.text;
     [self.navigationController popToRootViewControllerAnimated:YES];
 }
 
 @end

    單例類.h文件：

     #import <Foundation/Foundation.h>
 
 @interface DanLi : NSObject
 
 //創(chuàng)建一個(gè)單例//如果在單線程里可以用nonatomic,如果在多線程里一定要用atomic,保證是只有一個(gè)在調(diào)用,不然在多線程里面如果多個(gè)方法調(diào)用修改單例類里的屬性時(shí)會(huì)沖突
 @property (atomic, copy) NSString *value;
 
 + (DanLi *)sharedDanLi;
 
 @end

    單例類.m文件：

     #import "DanLi.h"
 
 static DanLi *danli = nil;
 
 @implementation DanLi
 
 //實(shí)現(xiàn)方法,判斷是否為空,是就創(chuàng)建一個(gè)全局實(shí)例給它
 + (DanLi *)sharedDanLi {
     
     if (danli == nil) {
         danli = [[DanLi alloc] init];
     }
     return danli;
 }
 
 //避免alloc/new創(chuàng)建新的實(shí)例變量--->增加一個(gè)互斥鎖
 + (id)allocWithZone:(struct _NSZone *)zone {
     
     @synchronized(self) {
         if (danli == nil) {
             danli = [super allocWithZone:zone];
         }
     }
     return danli;
 }
 
 //避免copy,需要實(shí)現(xiàn)NSCopying協(xié)議
 - (id)copyWithZone:(NSZone *)zone {
     return self;
 }
 
 @end

  7. KVC傳值
    用法：正向傳值
    需求：當(dāng)A-push到B時(shí)，B中有一個(gè)Label需要顯示從A中的一個(gè)TextField輸入的內(nèi)容，這時(shí)我們需要用到正向傳值。

    A控制器.m文件：

     #import "A_ViewController.h"
 #import "B_ViewController.h"
 
 @interface A_ViewController ()
 
 @property (nonatomic, strong) UITextField *aTextField;
 
 @end
 
 @implementation A_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     // Do any additional setup after loading the view.
     self.title = @"A";
     self.view.backgroundColor = [UIColor whiteColor];
     self.aTextField = [[UITextField alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];
     
     self.aTextField.layer.borderColor = [UIColor grayColor].CGColor;
     self.aTextField.layer.borderWidth = 1;
     [self.view addSubview:self.aTextField];
     
     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
     button.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 280, 100, 30);
     [button setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
     [button setTitle:@"傳到B" forState:UIControlStateNormal];
     [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:button];
 }

 - (void)buttonAction:(UIButton *)sender {
 
     B_ViewController *bViewController = [[B_ViewController alloc] init];
 
     /**
         KVC 傳值：這里只能傳A傳到B （因?yàn)?B在A頁面提前初始化）
         B 有個(gè)屬性 string
         用B對象 給B屬性賦值（回顧下OC中KVC賦值 就理解了）
      
         這里forkey 一定要和B 屬性名字一致 （也可以用@"_string"）因?yàn)槭菍傩?      */
     
     // 給B屬性string  賦值
     [bViewController setValue:self.aTextField.text forKey:@"string"];
     
     [self.navigationController pushViewController:bViewController animated:YES];
 }
 
 @end

    B控制器.h文件：

     #import <UIKit/UIKit.h>
 
 @interface B_ViewController : UIViewController
 
 @property (nonatomic, copy) NSString *string;
 
 @end

    B控制器.m文件：

     #import "B_ViewController.h"
 
 @interface B_ViewController ()
 
 @end
 
 @implementation B_ViewController
 
 - (void)viewDidLoad {
     [super viewDidLoad];
     
     self.title = @"B";
     self.view.backgroundColor = [UIColor whiteColor];
     
     self.view.backgroundColor = [UIColor whiteColor];
     UILabel *bLabel = [[UILabel alloc] initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 200, 100, 30)];
     
     bLabel.layer.borderColor = [UIColor grayColor].CGColor;
     bLabel.layer.borderWidth = 1;
     [self.view addSubview:bLabel];
     
     UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
     button.frame = CGRectMake([UIScreen mainScreen].bounds.size.width/2-50, 280, 100, 30);
     [button setTitleColor:[UIColor grayColor] forState:UIControlStateNormal];
     [button setTitle:@"傳值A(chǔ)" forState:UIControlStateNormal];
     [button addTarget:self action:@selector(buttonAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:button];
     
     // KVC 接收值
     bLabel.text = self.string;
 }
 
 - (void)buttonAction:(UIButton *)sender {
     
     [self.navigationController popToRootViewControllerAnimated:YES];
 }
 
 @end

好了，到此已經(jīng)基本上介紹完頁面?zhèn)髦盗?，相信你對頁面?zhèn)髦狄呀?jīng)有一定理解了吧，快去實(shí)踐吧！

最后編輯于 ：
?著作權(quán)歸作者所有,轉(zhuǎn)載或內(nèi)容合作請聯(lián)系作者
【社區(qū)內(nèi)容提示】社區(qū)部分內(nèi)容疑似由AI輔助生成，瀏覽時(shí)請結(jié)合常識與多方信息審慎甄別。
平臺聲明：文章內(nèi)容（如有圖片或視頻亦包括在內(nèi)）由作者上傳并發(fā)布，文章內(nèi)容僅代表作者本人觀點(diǎn)，簡書系信息發(fā)布平臺，僅提供信息存儲服務(wù)。

相關(guān)閱讀更多精彩內(nèi)容

友情鏈接更多精彩內(nèi)容