windowLevel使用实例

1.UIWindow的windowLevel有三个取值

UIWindowLevelAlert:值为2000，同对话框的层级
UIWindowLevelStatusBar:值为1000,是状态栏的层级
UIWindowLevelNormal:：值为0.000000,是默认值，
注意：值越大显示的越靠上。

2.懒加载

- (UILabel *)topLable
{
    if(_topLable == NULL)
    {
        _topLable = [[UILabel alloc] initWithFrame:CGRectMake(0, -60, LYWIDTH, 60)];
        _topLable.backgroundColor = [UIColor grayColor];
        _topLable.textColor = [UIColor blackColor];
        _topLable.font = [UIFont fontWithName:LYCOMMON_FONT_NAME size:LYWeatherName_textF];
        _topLable.textAlignment = NSTextAlignmentCenter;
    }
    return _topLable;
}

3.实现从状态栏之上划入一个视图

self.window.windowLevel = UIWindowLevelAlert;
    
    [self.window  addSubview:self.topLable];
    self.topLable.text = @"接收本地通知啦";
    
    [UIView animateWithDuration:1.0 animations:^{
        self.topLable.frame = CGRectMake(0, 0, LYWIDTH, 60);
    } completion:^(BOOL finished)
     {

         [UIView animateWithDuration:1.0 delay:2.0 options:UIViewAnimationOptionCurveEaseInOut animations:^{

             self.topLable.frame = CGRectMake(0, -60, LYWIDTH, 60);
             
         } completion:^(BOOL finished) {
             self.window.windowLevel = UIWindowLevelNormal;

         }];
         
     }];

4.实现从状态栏之上划入一个视图

window的windowLevel改为UIWindowLevelNormal即可