addConstraints
添加约束的步奏
- 添加控件到view中
- 设置translateResizeLayoutintoautolayout = false
- 添加约束
注意
约束 : 出现 有父子关系的约束时候
【父 addConstarints 子】
注意
/**
* 两个子控件不可以添加相对的view
必须是
父亲 = 子 * mul +constant
*/
// 相对约束
// NSLayoutConstraint * blueRight = [NSLayoutConstraint constraintWithItem:blueview attribute:NSLayoutAttributeLeftMargin relatedBy:NSLayoutRelationEqual toItem:redview attribute:NSLayoutAttributeRightMargin multiplier:0.0f constant:50];
//
// [blueview addConstraint: blueRight];
// [redview addConstraint: blueRight];
报出来的错误
[NSLayoutConstraint constraintWithItem:attribute:relatedBy:toItem:attribute:multiplier:constant:]: A multiplier of 0 or a nil second item together with a location for the first attribute creates an illegal constraint of a location equal to a constant. Location attributes must be specified in pairs'