UITextField详解-优快云博客

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1、基本用法：

    UITextField * textField = [[UITextField alloc] initWithFrame:CGRectMake(30, 100, 200, 30)];
    textField.backgroundColor = [UIColor whiteColor];
    [self.view addSubview:textField];
    textField.text = @"预置文字";
    textField.borderStyle = UITextBorderStyleRoundedRect;//设置输入框的边框类型为圆角

效果：

2、UITextField的边框类型：

typedef NS_ENUM(NSInteger, UITextBorderStyle) {
    UITextBorderStyleNone,
    UITextBorderStyleLine,
    UITextBorderStyleBezel,
    UITextBorderStyleRoundedRect
};

上面1中是最后一种（圆角+阴影），下面看看其他三种

（1）、textField.borderStyle = UITextBorderStyleNone 无边框线

（2）、textField.borderStyle = UITextBorderStyleBezel 边框线 + 阴影（效果可能不是很明显）

（3）、textField.borderStyle = UITextBorderStyleLine 仅有边框线

3、键盘的显示和隐藏

只要让textField变为第一响应者键盘就会显示，反之如果textField失去第一响应者，键盘就会隐藏。

@interface ViewController () <UITextFieldDelegate>

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    self.view.backgroundColor = [UIColor brownColor];
    
    UITextField * textField = [[UITextField alloc] initWithFrame:CGRectMake(30, 100, 200, 30)];
    textField.backgroundColor = [UIColor whiteColor];
    [self.view addSubview:textField];
    textField.text = @"预置文字";
    textField.borderStyle = UITextBorderStyleRoundedRect;//设置输入框的边框类型为圆角    
    textField.delegate = self;
}
//点击键盘return键，让textField失去第一响应者，隐藏键盘，使用这个方法要设置代理UITextFieldDelegate
- (BOOL)textFieldShouldReturn:(UITextField *)textField {
    [textField resignFirstResponder];
    return YES;
}

让textField成为第一响应者：

点击return使其失去第一响应者并隐藏键盘：

至于键盘类型，这里不再继续说，因为主要要说UITextField

4、文本的位置调整

首先将textField的高度调整为50，这样看着比较明显，然后设置textField的textAlignment属性

/* Values for NSTextAlignment */
typedef NS_ENUM(NSInteger, NSTextAlignment) {
    NSTextAlignmentLeft      = 0,    // Visually left aligned
#if TARGET_OS_IPHONE
    NSTextAlignmentCenter    = 1,    // Visually centered
    NSTextAlignmentRight     = 2,    // Visually right aligned
#else /* !TARGET_OS_IPHONE */
    NSTextAlignmentRight     = 1,    // Visually right aligned
    NSTextAlignmentCenter    = 2,    // Visually centered
#endif
    NSTextAlignmentJustified = 3,    // Fully-justified. The last line in a paragraph is natural-aligned.
    NSTextAlignmentNatural   = 4,    // Indicates the default alignment for script
} NS_ENUM_AVAILABLE_IOS(6_0);

什么都不设置，默认：

（1）、textField.textAlignment = NSTextAlignmentLeft

（2）、textField.textAlignment = NSTextAlignmentCenter

（3）、textField.textAlignment = NSTextAlignmentRight

（4）、textField.textAlignment = NSTextAlignmentJustified

（5）、textField.textAlignment = NSTextAlignmentNatural

5、文本的横向与纵向的调整

（1）、横向调整，横向调整可以参考4

（2）、纵向调整，改变UITextField的contentVerticalAlignment属性

typedef NS_ENUM(NSInteger, UIControlContentVerticalAlignment) {
    UIControlContentVerticalAlignmentCenter  = 0,
    UIControlContentVerticalAlignmentTop     = 1,
    UIControlContentVerticalAlignmentBottom  = 2,
    UIControlContentVerticalAlignmentFill    = 3,
};

textField.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter

textField.contentVerticalAlignment = UIControlContentVerticalAlignmentTop

textField.contentVerticalAlignment = UIControlContentVerticalAlignmentBottom

textField.contentVerticalAlignment = UIControlContentVerticalAlignmentFill

6、设置输入框的字体及颜色

    textField.font = [UIFont systemFontOfSize:30];
    textField.textColor = [UIColor redColor];

7、提示信息

    textField.placeholder = @"这是提示信息";

注意：如果需要设置提示信息，那就不能设置UITextField的text属性，否则提示信息不会显示，只会显示设置的text文本信息

8、清空按钮

（1）、textField.clearButtonMode = UITextFieldViewModeNever （这个也是默认，不显示清空按钮）
（2）、textField.clearButtonMode = UITextFieldViewModeWhileEditing （编辑的时候显示，否则不显示）

（3）、textField.clearButtonMode = UITextFieldViewModeUnlessEditing （编辑时不显示，不编辑时显示）
编辑时，就是为第一响应者：

失去第一响应者：

（4）、textField.clearButtonMode = UITextFieldViewModeAlways （总是显示）

9、设置背景图片：

注意：只有把textField.borderStyle 设置为 UITextBorderStyleNone 的时候背景图片才会显示，切记

    UIImage * image = [UIImage imageNamed:@"bg.png"];
    UIImage * stretchImage = [image stretchableImageWithLeftCapWidth:30 topCapHeight:25]; 
    textField.background = stretchImage;

这里如果同时backgroundColor，则backgroundColor失效

设置 disabledBackground

    UIImage * image1 = [UIImage imageNamed:@"apple.jpg"];
    UIImage * stretchImage1 = [image1 stretchableImageWithLeftCapWidth:30 topCapHeight:25];    
    textField.disabledBackground = stretchImage1;
    textField.enabled = NO;//不可编辑，一定要设置这个    
    [self.view addSubview:textField];

这个背景图片拉伸后看着比较难看，见谅

10、追加UIView或者其子类

在文本输入框的左右侧可以追加任意的UIView及其子类，因为UITextField有leftView和rightView属性

    UIImage * imageLeft = [UIImage imageNamed:@"dog.png"];
    UIImage * imageRight = [UIImage imageNamed:@"apple.jpg"];
    UIImageView * imageViewLeft = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 50, 50)];
    imageViewLeft.image = imageLeft;
    UIImageView * imageViewRight = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 50, 50)];
    imageViewRight.image = imageRight;
    
    textField.leftView = imageViewLeft;
    textField.rightView = imageViewRight;
    textField.leftViewMode = UITextFieldViewModeAlways;//这里跟清空按钮的模式是一样的
    textField.rightViewMode = UITextFieldViewModeAlways;

把右边按钮

    textField.rightViewMode = UITextFieldViewModeUnlessEditing;

11、文本输入框的状态监视

通过向UITextField的delegate属性设置为self，并把当前类设置为遵从UITextFieldDelegate协议，通过UITextFieldDelegate协议中的各种方法监视UITextField的各种状态

@protocol UITextFieldDelegate <NSObject>

@optional

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField;        // return NO to disallow editing.
- (void)textFieldDidBeginEditing:(UITextField *)textField;           // became first responder
- (BOOL)textFieldShouldEndEditing:(UITextField *)textField;          // return YES to allow editing to stop and to resign first responder status. NO to disallow the editing session to end
- (void)textFieldDidEndEditing:(UITextField *)textField;             // may be called if forced even if shouldEndEditing returns NO (e.g. view removed from window) or endEditing:YES called

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string;   // return NO to not change text

- (BOOL)textFieldShouldClear:(UITextField *)textField;               // called when clear button pressed. return NO to ignore (no notifications)
- (BOOL)textFieldShouldReturn:(UITextField *)textField;              // called when 'return' key pressed. return NO to ignore.

@end

@interface ViewController () <UITextFieldDelegate>

@end

    textField.delegate = self;

- (BOOL)textFieldShouldReturn:(UITextField *)textField {
    //键盘上的return键被点击后调用
    [textField resignFirstResponder];
    return YES;
}

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField {
    //编辑开始前被调用
    //返回NO，不允许编辑，相当于textField.enabled = NO，返回YES允许编辑
    return YES;
}

- (void)textFieldDidBeginEditing:(UITextField *)textField {
    //文本框变为第一响应者之后调用
    NSLog(@"我已经变为第一响应者了");
}

- (BOOL)textFieldShouldEndEditing:(UITextField *)textField {
    //编辑结束前被调用
    //如果返回NO编辑将不会结束，一直处于编辑状态
    return YES;
}

- (void)textFieldDidEndEditing:(UITextField *)textField {
    NSLog(@"编辑结束后调用");
}


- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    //文本修改前被调用
    //range为修改范围，string为修改后的字符串，返回NO文本将不会被修改
    NSLog(@"%@", NSStringFromRange(range));
    NSLog(@"%@", string);
    return YES;
}

- (BOOL)textFieldShouldClear:(UITextField *)textField {
    //清除按钮被触摸的时候调用，返回YES输入框内容被清除，返回NO输入框内容不变
    return YES;
}

12、自定义UITextField的时候返回新的各个区域的区域范围（自定义UITextField的时候，可以重写这些方法，来重置这些区域的区域范围）

- (CGRect)borderRectForBounds:(CGRect)bounds;
- (CGRect)textRectForBounds:(CGRect)bounds;
- (CGRect)placeholderRectForBounds:(CGRect)bounds;
- (CGRect)editingRectForBounds:(CGRect)bounds;
- (CGRect)clearButtonRectForBounds:(CGRect)bounds;
- (CGRect)leftViewRectForBounds:(CGRect)bounds;
- (CGRect)rightViewRectForBounds:(CGRect)bounds;