菜鸟启航：UITextField基本操作（二）

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");
}

//询问，TextField是否可以结束编辑
- (BOOL)textFieldShouldEndEditing:(UITextField *)textField
{

NSLog(@"询问，TextField是否可以结束编辑");

return
YES;
}

- (void)textFieldDidEndEditing:(UITextField *)textField
{

NSLog(@"TextField被告知，已经结束编辑状态");
}

//询问，是否可以改变指定TextField的指定的range范围内的内容替换成指定的string
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range
replacementString:(NSString *)string
{

// if ([string isEqualToString:@"a"]) {

// return YES;

// }

NSString * originString = textField.text;
NSString * newString = [originString stringByReplacingCharactersInRange:range withString:string];

if (newString.length <
10) {

return YES;
}

return
NO;
}

//
- (BOOL)textFieldShouldClear:(UITextField *)textField
{

NSLog(@"询问是否可以清除内容");

return
NO;
}

- (BOOL)textFieldShouldReturn:(UITextField *)textField
{

NSLog(@"Return键被点击");

if (textField == self.tf) {
[self.pwtf becomeFirstResponder];
}

else {
[textField resignFirstResponder];
}

return
YES;
}