frame和bounds

区别：

frame:根据父视图坐标系来确定自己的位置
bounds:该视图在自己坐标系的位置和大小
            修改bounds并不会引起视图位置的变化，会影响自身子视图的位置；修改frame会引起视图位置的变化

UIView *view1 = [[UIView alloc] init];
view1.frame = CGRectMake(10, 10, 200, 200);
[self.wiew addSubview:view1];

UIView *view2 = [[UIView alloc] initWithFrame:CGRectMake(50, 50, 100, 100)];
    view2.backgroundColor = [UIColor yellowColor];
    [view1 addSubview:view2];

这时显示的视图是

UIView *view1 = [[UIView alloc] init];
view1.frame = CGRectMake(10, 10, 200, 200);
view1.bounds = CGRectMake(50, 50, 200, 200);
[self.wiew addSubview:view1];

UIView *view2 = [[UIView alloc] initWithFrame:CGRectMake(50, 50, 100, 100)];
    view2.backgroundColor = [UIColor yellowColor];
    [view1 addSubview:view2];

这时显示的视图是