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。