autolayout的各种坑

[_xibView mas_updateConstraints:^(MASConstraintMaker *make) {

make.top.offset(300);

make.width.offset(100);

make.height.offset(100);

}];

1. autolayout做动画需要调用系统方法

[self.view layoutIfNeeded];

例如:

[UIView animateWithDuration:0.5 animations:^{
//            CGRect rect = _xibView.frame;
//            rect.origin.y = 300;
//            _xibView.frame = rect;
//
            [_xibView mas_updateConstraints:^(MASConstraintMaker *make) {
                make.top.offset(300);
                make.width.offset(100);
                make.height.offset(100);
            }];
            [self.view layoutIfNeeded];
        } completion:^(BOOL finished) {

        }];

2. 没办法知道这个视图的真实尺寸

3. 难以修改或者这个视图的尺寸和位置约束