使用代理Delegate實現(xiàn)反向傳值

1)定義協(xié)議.方法
2)聲明一個屬性,記錄代理對象
3)在合適的時機(jī),給代理方發(fā)消息

BViewController.h

#import <UIKit/UIKit.h>
@class BViewController;

/** 定義協(xié)議 */
@protocol BViewControllerDelegate <NSObject>

/** 定義方法 */
-(void)BViewController:(BViewController *)bViewController didFinishInputMsg:(NSString *)msg;
@end

@interface BViewController : UIViewController

/** 聲明一個屬性,記錄代理對象 */
@property (nonatomic,weak) id<BViewControllerDelegate> delegate;
@end

BViewController.m

@interface BViewController ()
@property (weak, nonatomic) IBOutlet UITextField *textField;
@end

@implementation BViewController
- (void)viewDidLoad {
    [super viewDidLoad];
}

- (IBAction)clickDelegate:(id)sender {
    /** 界面dismiss前給代理方發(fā)消息 */
    [self.delegate BViewController:self didFinishInputMsg:self.textField.text];
    [self dismissViewControllerAnimated:YES completion:nil];
}
@end

AViewController.m

1)遵守協(xié)議
2)實現(xiàn)方法
3)設(shè)置代理

AViewController.m
#import "AViewController.h"
#import "BViewController.h"

/** 遵守BViewController協(xié)議 */
@interface AViewController ()<BViewControllerDelegate>
@property (weak, nonatomic) IBOutlet UILabel *label;
@end

@implementation AViewController
- (void)viewDidLoad {
    [super viewDidLoad];
}

/** 獲取storyboard segue 設(shè)置代理 */
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    BViewController *bViewContrller = segue.destinationViewController;
    bViewContrller.delegate = self;
}

#pragma mark - BViewControllerDelegate
/** 實現(xiàn)BViewControllerDelegate的方法 */
-(void)BViewController:(BViewController *)bViewController didFinishInputMsg:(NSString *)msg {
    self.label.text = msg;
}
@end

使用通知NSNotification實現(xiàn)反向傳值

BViewController.h

1)聲明全局通知名稱
2)發(fā)送全局通知

#import <UIKit/UIKit.h>
/** 聲明一個全局通知名稱 */
#define kNotificationDidFinishInputMsg @"kNotificationDidFinishInputMsg"

BViewController.m

@interface BViewController ()
@property (weak, nonatomic) IBOutlet UITextField *textField;
@end

@implementation BViewController
- (void)viewDidLoad {
    [super viewDidLoad];
}

- (IBAction)clickNotification:(id)sender {
    /** 發(fā)送全局通知 */
    [[NSNotificationCenter defaultCenter]postNotificationName:kNotificationDidFinishInputMsg object:@{@"msg" : self.textField.text}];
    [self dismissViewControllerAnimated:YES completion:nil];
}
@end

AViewController.m

1)收聽通知
2)注銷通知

#import "AViewController.h"
#import "BViewController.h"

@interface AViewController ()
@property (weak, nonatomic) IBOutlet UILabel *label;
@end

@implementation AViewController
- (void)viewDidLoad {
    [super viewDidLoad];

    /** 添加收聽者 */
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(getNotification:) name:kNotificationDidFinishInputMsg object:nil];    
}

/** 當(dāng)收到通知,實現(xiàn)該方法 */
-(void)getNotification:(NSNotification *)notification {
    self.label.text = notification.object[@"msg"];
}

/** dealloc方法里需注銷通知 */
-(void)dealloc {
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}
@end

使用block實現(xiàn)反向傳值

BViewController.h

1)聲明block
2)傳參

#import <UIKit/UIKit.h>

@interface BViewController : UIViewController
/** 聲明block */
@property (nonatomic,copy) void (^finishInputMsgBlock)(NSString *msg);
@end

BViewController.m

#import "BViewController.h"
@interface BViewController ()
@property (weak, nonatomic) IBOutlet UITextField *textField;
@end

@implementation BViewController
- (void)viewDidLoad {
    [super viewDidLoad];
}
- (IBAction)clickBlock:(id)sender {
    /** 傳入?yún)?shù) */
    self.finishInputMsgBlock(self.textField.text);
    [self dismissViewControllerAnimated:YES completion:nil];
}
@end

AViewController.m

1)推出界面時回調(diào)block

#import "AViewController.h"
#import "BViewController.h"
@interface AViewController ()
@property (weak, nonatomic) IBOutlet UILabel *label;
@end

@implementation AViewController
- (void)viewDidLoad {
    [super viewDidLoad];
}

/** 獲取storyboard segue 回調(diào)block */
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    BViewController *bViewContrller = segue.destinationViewController;
    bViewContrller.finishInputMsgBlock = ^(NSString *msg) {
        self.label.text = msg;
    };
}
@end