Masonry动画

// 告诉self.view约束需要更新[self.viewsetNeedsUpdateConstraints];

// 调用此方法告诉self.view检测是否需要更新约束，若需要则更新，下面添加动画效果才起作用[self.viewupdateConstraintsIfNeeded];

[UIViewanimateWithDuration:0.3animations:^{

[self.viewlayoutIfNeeded];

}];