Masonry布局

参考:https://www.jianshu.com/p/e3162f3c61fa

1,masonry进行线性布局

//首先添加5个视图
 NSMutableArray *array = [NSMutableArray new];
    for (int i = 0; i < 5; i ++) {
        UIView *view = [UIView new];
        view.backgroundColor = [UIColor greenColor];
        [self addSubview:view];
        [array addObject:view]; //保存添加的控件
    }

//水平方向控件间隔固定等间隔
[array mas_distributeViewsAlongAxis:MASAxisTypeHorizontal withFixedSpacing:15 leadSpacing:10 tailSpacing:10];
            [array makeConstraints:^(MASConstraintMaker *make) {
                make.top.equalTo(50);
                make.height.equalTo(70);
            }];

//水平方向宽度固定等间隔
[array mas_distributeViewsAlongAxis:MASAxisTypeHorizontal withFixedItemLength:70 leadSpacing:10 tailSpacing:10];
            [array makeConstraints:^(MASConstraintMaker *make) { //数组额你不必须都是view 
                make.top.equalTo(50);
                make.height.equalTo(70);
            }];

2，masonry不会造成循环引用的原因

传入的block直接就同步执行了，执行完block引入的变量引用计数又会释放。见如下代码:

- (NSArray *)mas_makeConstraints:(void(^)(MASConstraintMaker *))block {
    self.translatesAutoresizingMaskIntoConstraints = NO;
    MASConstraintMaker *constraintMaker = [[MASConstraintMaker alloc] initWithView:self];
    block(constraintMaker);
    return [constraintMaker install];
}