1.使用UILabel顯示靜態(tài)文本
想要給用戶顯示靜態(tài)文本，并且控制文本的字體和顏色。
@property(nonatomic,strong)UILabel *myLabel;
@synthesize myLabel;
-(void)viewDidLoad{
[super viewDidLoad];
self.view.backgroundColor = [UIColor whiteColor];
CGRect labelFrame = CGRectMake(0.0f,0.0f,100.0f,23.0f);
self.myLabel = [ [UILabel alloc]initWithFrame:labelFrame];
self.myLabel.text = @"hello world";
self.myLabel.font = [UIFont boldSystemFontOfSize:14.0f];
self.myLabel.numberOfLines = 3;//文本行數(shù)
self.myLabel.adjustsFontSizeToFitWidth = YES; //標簽視圖保持靜態(tài)，并且標簽里的字體能自動調(diào)整到適合標簽的邊界。
self.myLabel.center = self.view.center;
[self.view addSubview:self.myLabel];
}
使用UITextField接受用戶文本輸入（默認高度31像素）
@property( nonatomic,strong)UITextField *myTextField;
@synthesize myTextField;
-(void)viewDidLoad{
[super viewDidLoad];
self.view.backgroundColor = [UIColor whiteColor];
CGRect textFieldFrame = CGRectMake(0.0f,0.0f,200.0f,31.0f);
self.myTextField = [[UITextField alloc] initWithFrame:textFieldFrame];
self.myTextField.borderStyle = UITextBorderStyleRoundedRect;//文本視圖邊框
self.myTextField.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;//文本視圖縱向居中
self.myTextField.textAlignment = UITextAlignmentCenter;//文本水平對齊方式
self.myTextField.text = @"hello world";
self.myTextField.center = self.view.center;
[self.view addSubview:self.myTextField];
}
UITextFieldDelegate協(xié)議
textFieldShouldBeginEditing：//BOOL 設置文本視圖是否可編輯
textFieldDidBeginin: //當用戶開始編輯這個文本視圖時這個方法將會被調(diào)用。
textFieldShouldEndEditing: //這個方法返回一個BOOL值，它將告訴文本視圖是否結束當前的編輯進程。假如返回NO，用戶將不能終止文本的編輯。
textFieldDidEndEditing: 當文本視圖的編輯進程終止時將會被調(diào)用。
textField:shouldChangeCharacterInRange:replacementString: 任何時候文本視圖里的文本被修改都會調(diào)用這個方法。返回是一個布爾值，NO，文本視圖里的文本的修改將不會被通知和發(fā)生，YES，說明允許修改文本。
textFieldShouldClear:每個文本視圖都有一個clear按鈕，通常是一個圓形X按鈕。
textFieldShouldReturn:當用戶在鍵盤上按下return 或 enter 鍵時將會調(diào)用這個方法，嘗試隱藏鍵盤，你需要將這個文本視圖注冊為這個方法的第一個響應者。
@property(nonatomic,strong)UITextField *myTextField;
@property(nonatomic,strong)UILabel *labelCounter;
@synthesize myTextField;
@synthesize labelCounter;
-(void)calculateAndDisplayTextFieldLengthWithText:(NSString *)paramText{
NSString *characterOrCharacters = @"Characters";
if([paramText length] == 1){
characterOrCharacters = @"Character";
}
self.labelCounter.text = [NSString stringWithFormat:@"%lu %@",(unsigned long)[paramText length],characterOrCharacters];
}
-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
BOOL result = YES;
if([textField isEqual:self.myTextField]){
NSString *wholeText = [textField.text stringByReplacingCharactersInRange:range withString:string];
[self calculateAndDisplayTextFieldLengthWithText:wholeText];
}
return result;
}
-(BOOL)textFieldShouldReturn:(UITextField *)textField{
[textField resignFirstResponder];
return YES;
}
-(void)viewDidLoad{
[super viewDidLoad];
self.view.backgroundColor = [UIColor whileColor];
CGRect textFieldFrame = CGRectMake(38.0f,30.0f,220.0f,31.0f);
self.myTextField = [[UITextField alloc]initWithFrame:textFieldFrame];
self.myTextField.delegate = self;
self.myTextField.borderStyle = UITextBorderStyleRounderRect;
self.myTextField.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
self.myTextField.text = @"hello world";
self.myTextField.placeholder = @"Enter text here … ";
self.view addSubview:self.myTextField];
CGRect labelCounterFrame = self.myTextField.frame;
labelCounterFrame.origin.y += textFieldFrame.size.height + 10;
self.labelCounter = [ [UILabel alloc]initWithFrame:labelCounterFrame];
[self.view addSubview:self.labelCounter];
[self calculateAndDisplayTextFieldLengthWithText];
[self calculateAndDisplayTextFieldLengthWithText:selfTextField.text];
}
文本視圖有兩個相對屬性，它們分別是leftView和rightView。
UILabel *currencyLabel = [ [UILabel alloc]initWithFrame:CGRectZero];
currencyLabel.text = [ [ [NSNumberFormatter alloc]init]currencySymbol];
currencyLabel.font = self.myTextField.font;
[currencyLabel sizeToFit];
self.myTextField.leftView = currencyLabel;
self.myTextField.leftViewMode = UITextFieldViewModeAlways;
typedef enum{
UITextfieldViewModeNever,
UITextFieldViewModeWhileEditing,//假如已經(jīng)聲明一個值給它，當用戶編輯這個文本視圖時左視圖將會顯示。
UITextFieldViewModeUnlessEditing,//當用戶沒有在文本視圖里編輯文本時左視圖將會顯示，但是一旦開始編輯，做視圖將會消失。
UItextFieldViewModeAlways
}UITextFieldViewMode;
使用UITextView顯示文本域
@property( nonatomic,strong)? UItextView? *myTextView;
@synthesize myTextView;
-(void)viewDidLoad{
[super viewDidLoad];
self.view.backgroundColor = [UIColor whileColor];
self.myTextView = [[UITextView alloc]initWithFrame:self.view.bounds];
self.myTextView.text = @"hello world";
self.myTextView.font = [UIFont systemFontOfSize:16.0f];
self.view addSubView:self.myTextView];
}
現(xiàn)假如你點擊文本視圖，虛擬鍵盤遮蓋了文本視圖的區(qū)域。怎么辦呢？為了能彌補這個缺陷，我們需要監(jiān)聽一些待定通知：
UIKeyboardWillShowNotification //當鍵盤正準備顯示子屏幕上時這個通知將會被發(fā)送給任何部件，比如文本視圖。
UIKeyboardDidShowNotification //當鍵盤已經(jīng)顯示在屏幕上時將會發(fā)送這個通知。
UIKeyboardWIllHideNotification //當鍵盤即將被隱藏時將會發(fā)送通知
UIKeyboardDidHideNotification //當鍵盤完全隱藏時將會發(fā)送這個通知
所以我們的策略就是去發(fā)現(xiàn)鍵盤什么時候準備在屏幕上顯示然后以何種方式調(diào)整視圖。
-(void)handleKeyBoardDidShow:(NSNotification *)paramNotification{
NSValue *keyboardRectAsObject = [[paramNotification userInfo]objectForKey:UIKeyboardFrameEndUserInfoKey];/*get the frame of the keyboard*/
CGRect keyboardRect;
[keyboardRectAsObject getValue:&keyboardRect];/*place it in a CGRect*/
self.myTextView.contentInset = UIEdgeInsetsMake(0.0f,0.0f,? keyboarddRect.size.height,0.0f);
}
-(void)handleKeyboardWillHide:(NSNotification *)paramNotification{
self.myTextView.contentInset = UIEdgeInsetsZero;/*make the text view as the whole view again*/
}
-(void)viewWillAppear:(BOOL)paramAnimated{
[super viewWillAppear:paramAnimated];
[ [NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleKeyboardDidShow:) name:UIKeyboardDidShowNotification object:nil];
[ [NSNotificationCenter defaultCenter] addObserver:self selector:@selector(handleKeyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
self.view.backgroundColor = [UIColor whiteColor];
self.myTextView = [ [UITextView alloc] initWithFrame:self.view.bounds];
self.myTextView.text = @""hello world……;
self.myTextView.font = [UIFont systemFontOfSize:16.0f];
[self.view addSubview: self.myTextView];
}
-(void)viewWillDisappear:(BOOL)paramAnimated{
[super viewWillDisappear:paramAnimated];
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
在這段代碼中，在方法 viewWillAppear：開始建通鍵盤通知，在方法viewWillDisappear 結束監(jiān)聽。
