Question

我尝试以编程方式将视图添加到UIScrollView，以便在调整子视图大小时，UIScrollView contentSize将自动匹配。

我试过这个：

private var _contentView = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))

addSubview(_contentView)



let leading = NSLayoutConstraint(item: _contentView, attribute: NSLayoutAttribute.Leading, relatedBy: NSLayoutRelation.Equal, toItem: self, attribute: NSLayoutAttribute.Leading, multiplier: 1, constant: 0)
let trailing = NSLayoutConstraint(item: _contentView, attribute: NSLayoutAttribute.Trailing, relatedBy: NSLayoutRelation.Equal, toItem: self, attribute: NSLayoutAttribute.Trailing, multiplier: 1, constant: 0)
let top = NSLayoutConstraint(item: _contentView, attribute: NSLayoutAttribute.Top, relatedBy: NSLayoutRelation.Equal, toItem: self, attribute: NSLayoutAttribute.Top, multiplier: 1, constant: 0)
let bottom = NSLayoutConstraint(item: _contentView, attribute: NSLayoutAttribute.Bottom, relatedBy: NSLayoutRelation.Equal, toItem: self, attribute: NSLayoutAttribute.Bottom, multiplier: 1, constant: 0)

self.addConstraints([leading,trailing,top,bottom])

但是我在运行时遇到一个关于无法满足约束的错误。

我也尝试使用可视格式设置约束并得到类似的错误：

let viewsDictionary = ["contentView":_contentView]

let hConstraints = NSLayoutConstraint.constraintsWithVisualFormat("H:|-0-[contentView]-0-|", options: NSLayoutFormatOptions.DirectionLeadingToTrailing, metrics: nil, views: viewsDictionary)
let vConstraints = NSLayoutConstraint.constraintsWithVisualFormat("V:|-0-[contentView]-0-|", options: NSLayoutFormatOptions.DirectionLeadingToTrailing, metrics: nil, views: viewsDictionary)

self.addConstraints(hConstraints)
self.addConstraints(vConstraints)

如何正确添加约束？

Answer 1

尝试在内容视图中将translatesAutoresizingMaskIntoConstraints设置为NO / false。

如果是滚动视图，子视图需要具有内在内容大小或显式宽度和高度约束，以允许滚动视图确定其内容大小。

因此，请尝试在内容视图中添加宽度和高度限制。

为添加到UIScrollView的视图设置约束？

1 个答案: