1、把需要改的約束Constraint拖條線出來管跺，成為屬性
2义黎、在需要?jiǎng)赢嫷牡胤郊尤氪a，改變此屬性的constant屬性
3豁跑、開始做UIView動(dòng)畫廉涕，動(dòng)畫里邊調(diào)用layoutIfNeeded方法
@property(weak, nonatomic)IBOutletNSLayoutConstraint *buttonTopConstraint;
self.buttonTopConstraint.constant =100;
[UIView animateWithDuration:.5animations:^{
? ? [self.view layoutIfNeeded];
}];
