Question

我有一个类型为UIView的self.photoView，我有一个UImageView的photoImageView。我想将photoImageView X和Y置于self.photoView中心。

此代码没有做任何事情！

let photoImageView = UIImageView.imageViewForPhotoTaken(self.photoView.bounds, image: img)
            photoImageView.contentMode = UIViewContentMode.ScaleAspectFit

            self.photoView.addSubview(photoImageView)

            // set the autolayout constraints 
            self.photoView.addConstraint(NSLayoutConstraint(item: self.photoView, attribute: NSLayoutAttribute.CenterX, relatedBy: NSLayoutRelation.Equal, toItem: photoImageView, attribute: NSLayoutAttribute.CenterX, multiplier: 1.0, constant: 0))

Answer 1

在添加约束之前，您需要在translatesAutoresizingMasksIntoConstraints = false和photoView上致电photoImageView。

Answer 2

试试这段代码：

let photoImageView = UIImageView(image:UIImage(named: "logo"))
photoImageView.contentMode = UIViewContentMode.ScaleAspectFit
self.photoView.addSubview(photoImageView)
photoImageView.translatesAutoresizingMaskIntoConstraints = false

// set the autolayout constraints
self.photoView.addConstraint(NSLayoutConstraint(item: photoImageView, attribute: .CenterX, relatedBy: .Equal, toItem: self.photoView, attribute: .CenterX, multiplier: 1, constant: 0))
self.photoView.addConstraint(NSLayoutConstraint(item: photoImageView, attribute: .CenterY, relatedBy: .Equal, toItem: self.photoView, attribute: .CenterY, multiplier: 1, constant: 0))

如果你想要水平和垂直中心，你应该设置'中心X'和'中心Y'约束

另外，请确保在设置此

之前为'self.photoView'设置了适当的约束

你应该把这段代码放在'viewDidAppear'或者在此之后调用的任何方法

使用Autolayout约束在父视图中居中视图

2 个答案: