iOS应用开发中监听键盘事件的代码实例小结

1.注册监听键盘事件的通知

    [[NSNotificationCenter defaultCenter] addObserver:self

                                             selector:@selector(keyboardWillShow:)

                                                 name:UIKeyboardWillShowNotification

                                               object:nil];

    

    [[NSNotificationCenter defaultCenter] addObserver:self

                                             selector:@selector(keyboardShow:)

                                                 name:UIKeyboardDidShowNotification

                                               object:nil];

    

    [[NSNotificationCenter defaultCenter] addObserver:self

                                             selector:@selector(keyboardWillHide:)

                                                 name:UIKeyboardWillHideNotification

                                               object:nil];

    

    [[NSNotificationCenter defaultCenter] addObserver:self

                                             selector:@selector(keyboardHide:)

                                                 name:UIKeyboardDidHideNotification

                                               object:nil];

2.在键盘将要出现和隐藏的回调中，加入动画

- (void)keyboardWillShow:(NSNotification *)notif {

    if (self.hidden == YES) {

        return;

    }

    

    CGRect rect = [[notif.userInfo objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];

    CGFloat y = rect.origin.y;

    [UIView beginAnimations:nil context:nil];

    [UIView setAnimationDuration:0.25];

    NSArray *subviews = [self subviews];

    for (UIView *sub in subviews) {

        

        CGFloat maxY = CGRectGetMaxY(sub.frame);

        if (maxY > y - 2) {

            sub.center = CGPointMake(CGRectGetWidth(self.frame)/2.0, sub.center.y - maxY + y - 2);

        }

    }

    [UIView commitAnimations];

}
- (void)keyboardShow:(NSNotification *)notif {

    if (self.hidden == YES) {

        return;

    }

}
- (void)keyboardWillHide:(NSNotification *)notif {

    if (self.hidden == YES) {

        return;

    }

    [UIView beginAnimations:nil context:nil];

    [UIView setAnimationDuration:0.25];

    NSArray *subviews = [self subviews];

    for (UIView *sub in subviews) {

        if (sub.center.y < CGRectGetHeight(self.frame)/2.0) {

            sub.center = CGPointMake(CGRectGetWidth(self.frame)/2.0, CGRectGetHeight(self.frame)/2.0);

        }

    }

    [UIView commitAnimations];

}
- (void)keyboardHide:(NSNotification *)notif {

    if (self.hidden == YES) {

        return;

    }

}

3.监听键盘删除键之非代理实现
在UITextField 和 UITextView ，如何监听到删除键。

我看到网上都是用代理监听的，我觉得不靠谱。

其实苹果已经写的很清楚了。

就在他们实现的协议里面～～

NS_CLASS_AVAILABLE_IOS(2_0) @interface UITextView : UIScrollView<UITextInput>

@protocol UITextInput<UIKeyInput>

@protocol UIKeyInput <UITextInputTraits>

- (BOOL)hasText;
- (void)insertText:(NSString *)text;
- (void)deleteBackward;
@end

写的非常清楚，一看就明白。

－deleteBackward 这个方法就是删除按钮监听。

只要自己写个子类，重写此方法就能监听。

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