菜鸟启航：UITextField基本操作（二）

最新推荐文章于 2020-09-20 08:20:04 发布

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最新推荐文章于 2020-09-20 08:20:04 发布

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CC 4.0 BY-SA版权

文章标签： IOS uitextfield 初学者

本文链接：https://blog.youkuaiyun.com/cozinessWestWing/article/details/48264225

本文介绍了如何通过继承UITextField来自定义其绘制和位置属性，并详细解释了UITextFieldDelegate协议的方法及其应用场景，包括键盘显示隐藏的通知处理。

一、继承UITextField的类

// drawing and positioning overrides

- (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;

- (void)drawTextInRect:(CGRect)rect;

- (void)drawPlaceholderInRect:(CGRect)rect;

////边框的坐标和大小

//- (CGRect)borderRectForBounds:(CGRect)bounds

//{

// //边框的大小

// //缩减

// NSLog(@"before: %@",NSStringFromCGRect(bounds));

// CGRect rect = CGRectInset(bounds, 50, 10);

// NSLog(@"after: %@",NSStringFromCGRect(rect));

// return rect;

//}

////非编辑状态下，文本的显示区域

//- (CGRect)textRectForBounds:(CGRect)bounds

//{

// return CGRectInset(bounds, 50, 10);

//}

////占位符的显示区域

//- (CGRect)placeholderRectForBounds:(CGRect)bounds

//{

// return CGRectMake(50, 10, 200, 40);

//}

////编辑状态下，文本的显示区域

//- (CGRect)editingRectForBounds:(CGRect)bounds

//{

// return CGRectInset(bounds, 50, 10);

//}

//- (CGRect)clearButtonRectForBounds:(CGRect)bounds;

//{

// return CGRectOffset(bounds, -50, 0);

//}

//- (CGRect)leftViewRectForBounds:(CGRect)bounds;

//- (CGRect)rightViewRectForBounds:(CGRect)bounds;

- (void)drawTextInRect:(CGRect)rect

{

[super drawTextInRect:CGRectInset(rect, 50, 10)];

}

- (void)drawPlaceholderInRect:(CGRect)rect

{

[super drawPlaceholderInRect:CGRectInset(rect, 50, 10)];

}

二、通知中心

//通知中心

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyBoardShowNotification:) name:UIKeyboardWillShowNotification object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyBoardHideNotification:) name:UIKeyboardWillHideNotification object:nil];

}

- (void)keyBoardShowNotification:(NSNotification *)notificaiton

{

NSLog(@"键盘显示");

[UIView animateWithDuration:1.0 animations:^{

self.button.frame = CGRectOffset(self.button.frame, 0, -100);

}];

}

- (void)keyBoardHideNotification:(NSNotification *)notificaiton

{

NSLog(@"键盘隐藏");

[UIView animateWithDuration:1.0 animations:^{

self.button.frame = CGRectOffset(self.button.frame, 0, 100);

}];

}

三、协议UITextFieldDelegate

self.tf.delegate = self;

协议可选实现方法

@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

//询问delegate我是否可以进行编辑

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField

{

return YES;

}

- (void)textFieldDidBeginEditing:(UITextField *)textField

{

NSLog(@"Delegate 被告知，TextField已经处于编辑状态,请指示");

}