Masonry约束优先级

两个控件之间约束优先级

以两个label 为例

UILabel *label1 = UILabel.new;
    label1.text = @"label1";
    label1.backgroundColor = [[UIColor alloc]initWithRed:arc4random_uniform(255)/255.0 green:arc4random_uniform(255)/255.0 blue:arc4random_uniform(255)/255.0 alpha:1];
    [self.view addSubview:label1];
    [label1 mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.offset(10);
        make.top.offset(100);
    }];
    
    UILabel *label2 = UILabel.new;
    label2.text = @"label2";
    label2.backgroundColor = [[UIColor alloc]initWithRed:arc4random_uniform(255)/255.0 green:arc4random_uniform(255)/255.0 blue:arc4random_uniform(255)/255.0 alpha:1];
    [self.view addSubview:label2];
    [label2 mas_makeConstraints:^(MASConstraintMaker *make) {
        make.right.offset(-10);
        make.centerY.equalTo(label1);
        make.left.mas_equalTo(label1.mas_right).offset(10);
    }];

默认展示

设置label2为高优先级

    [label1 setContentHuggingPriority:UILayoutPriorityDefaultLow forAxis:(UILayoutConstraintAxisHorizontal)];
    [label2 setContentHuggingPriority:UILayoutPriorityRequired forAxis:(UILayoutConstraintAxisHorizontal)];

如果文字变长了

    label1.text = @"label1-123456789qwertyuiop";
    label2.text = @"label2-123456789qwertyuiop";

默认

设置压缩label2

    [label1 setContentCompressionResistancePriority:UILayoutPriorityRequired forAxis:(UILayoutConstraintAxisHorizontal)];
    [label2 setContentCompressionResistancePriority:UILayoutPriorityDefaultLow forAxis:(UILayoutConstraintAxisHorizontal)];