在代碼裏更新autolayout佈局

 1             //遍歷view約束(高,寬)
 2             NSArray* constrains = self.View.constraints;
 3             for (NSLayoutConstraint* constraint in constrains) {
 4                 if (constraint.firstAttribute == NSLayoutAttributeHeight) {
 5                     //寬高的值
 6                     constraint.constant = 45.0;
 7                 }
 8             }
 9             
10            //遍歷view約束，找到屬於子view的約束
11             NSArray* constrains2 = self.view.constraints;
12             for (NSLayoutConstraint* constraint in constrains2) {
13                 if (constraint.secondItem == self.table) {
14                     //底部距離
15                     if (constraint.firstAttribute == NSLayoutAttributeBottom) {
16                         constraint.constant = 0.0;
17                         
18                     }
19                 }
20             }            

內容來自網絡，並部分修改，非我的原創。