Masonry约束立即生效跟约束更新

view1 = [UIView new];

    [self.view addSubview:view1];
    [view1 mas_makeConstraints:^(MASConstraintMaker *make) {
        make.edges.equalTo(self.view).insets(UIEdgeInsetsMake(10, 10, 10, 10));
    }];
    view1.backgroundColor  =  [UIColor redColor];
    NSLog(@"%@",view1.description);

打印结果是：

<UIView: 0x7f9d20d0b650; frame = (0 0; 0 0); layer = <CALayer: 0x608000227900>>

在mas_makeConstraints之后用它的父视图调用layoutIfNeeded可以使得约束立即生效：

    view1 = [UIView new];
    [self.view addSubview:view1];
    [view1 mas_makeConstraints:^(MASConstraintMaker *make) {
        make.edges.equalTo(self.view).insets(UIEdgeInsetsMake(10, 10, 10, 10));
    }];
    view1.backgroundColor   =   [UIColor redColor];
    [self.view layoutIfNeeded];
    NSLog(@"%@",view1.description);

打印结果是：

<UIView: 0x7fa8d8d05730; frame = (10 10; 394 716); layer = <CALayer: 0x60800003ca20>>