NSLayoutConstraint constraintWithVisualFormat无法引用superView

Question

以下是一些代码：

UIView *c = [[UIView alloc] initWithFrame:CGRectZero];
[self addSubview:c];
c.translatesAutoresizingMaskIntoConstraints = NO;
c. backgroundColor = [UIColor lightGrayColor];
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[c(>=600)]-|" options:NSLayoutFormatDirectionLeadingToTrailing metrics:nil views:NSDictionaryOfVariableBindings(c)]] ;
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[c]|" options:NSLayoutFormatDirectionLeadingToTrailing metrics:nil views:NSDictionaryOfVariableBindings(c)]] ;![enter image description here][1]

为什么它看起来像这样？是什么东西搞砸了我的superView？

以下是我的包含视图的设置方式：

Answer 1

c的超级视图是self。不是self.superview。

所以这些行应该是：

[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[c]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(c)]] ;
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[c]-0-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(c)]] ;

此外，UIView的指定初始化程序为-initWithFrame:，只是调用init并不能保证正常工作。所以第一行应该是

UIView *c = [[UIView alloc] initWithFrame:CGRectZero];

Answer 2

确定。它现在看起来像约束失败是因为持有一切的视图是UIScrollView的子类。