iOS应用开发中监听键盘事件的代码实例小结
作者：心有思
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。