// 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];
}];
// 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];
}];