## iOS 中用了autolayout遮挡键盘的处理 ##

iOS 中用了autolayout遮挡键盘的处理

先说明我的情况：1.我是用了masonry 和iOS自带的autolayout结合的 简单的登录问题

loginView是我的一个登录背景，，设置的居中，，当我点击输入的时候，，我会判断键盘是否会遮挡我的loginView,如果不会遮挡，，我就不需要改变loginView的frame，，，在autolayout中，如果要获取正确的frame的一定要在viewDidAppear 方法中，，总之是要在viewDidAppear方法以后才可以。

-(void)viewDidLoad
{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShowNotification:) name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHideNotification:) name:UIKeyboardWillHideNotification object:nil];


}

#pragma mark - Notification center
- (void)keyboardWillShowNotification:(NSNotification *)notification {
    // 获取键盘基本信息（动画时长与键盘高度）
    NSDictionary *userInfo = [notification userInfo];

    NSLog(@"log:%@",NSStringFromCGRect(self.loginView.frame));

    NSLog(@"%@",userInfo);

    CGRect rect = [userInfo[UIKeyboardFrameBeginUserInfoKey] CGRectValue];
    CGFloat keyboardHeight = CGRectGetHeight(rect)-(CGRectGetHeight(self.view.frame)-self.loginView.frame.origin.y-CGRectGetHeight(self.loginView.frame));
    CGFloat keyboardDuration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    //判断视图是否被键盘遮挡住了
    if (keyboardHeight>0) {
        // 修改边距约束
        [self.loginView mas_updateConstraints:^(MASConstraintMaker *make) {

            make.centerY.mas_equalTo(self.view).offset(-keyboardHeight);
        }];

        // 更新约束
        [UIView animateWithDuration:keyboardDuration animations:^{
            [self.view layoutIfNeeded];
        }];
    }
}

- (void)keyboardWillHideNotification:(NSNotification *)notification {
    // 获得键盘动画时长
    NSDictionary *userInfo = [notification userInfo];
    CGFloat keyboardDuration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];

    // 修改为以前的约束（距下边距0）
    [self.loginView mas_updateConstraints:^(MASConstraintMaker *make) {
        make.center.mas_equalTo(self.view);
    }];

    // 更新约束
    [UIView animateWithDuration:keyboardDuration animations:^{
        [self.view layoutIfNeeded];
    }];
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    [super touchesBegan:touches withEvent:event];
    [self.view endEditing:YES];
}

- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillChangeFrameNotification object:nil];
}