快速水平和垂直对齐图像

Question

我想将另一个图像（水平和垂直）对齐以创建动画。动画很简单：心脏会在 Angry Bedou 的标志内“振动”，但他必须在该图像中“居中”。

我正在尝试以下方法：

    func animate() {
    heartImg.frame = CGRectMake(angryBedousImg.frame.size.width / 2, angryBedousImg.frame.size.height / 2, heartImg.frame.size.width, heartImg.frame.size.height)

    let heartAnimation = CABasicAnimation(keyPath: "position")
    heartAnimation.duration = 0.09
    heartAnimation.repeatCount = .infinity
    heartAnimation.autoreverses = true
    heartAnimation.fromValue = NSValue(CGPoint: CGPointMake(heartImg.center.x - 1, heartImg.center.y))
    heartAnimation.toValue = NSValue(CGPoint: CGPointMake(heartImg.center.x + 1, heartImg.center.y))
    heartImg.layer.addAnimation(heartAnimation, forKey: "position")
        }

但是当我构建应用程序时它不会集中。动画有效，但对齐无效。我希望在纵向模式下在每个设备中进行对齐工作。

我看了故事板，图像很好。我做错了什么？

Answer 1

试试这个：

这将使您的 heartImage 以背景图像为中心。

    let yourImage = UIImage(named: "YourImageName")
    let heartImg = UIImageView()
    heartImg.image = yourImage
    heartImg.translatesAutoresizingMaskIntoConstraints = false
    self.view.addSubview(heartImg)
    self.view.addConstraint(NSLayoutConstraint(item: heartImg, attribute: NSLayoutAttribute.centerX, relatedBy: NSLayoutRelation.equal, toItem: self.yourLogoImage, attribute: NSLayoutAttribute.centerX, multiplier: 1.0, constant: 0))
    self.view.addConstraint(NSLayoutConstraint(item: heartImg, attribute: NSLayoutAttribute.centerY, relatedBy: NSLayoutRelation.equal, toItem: self.yourLogoImage, attribute: NSLayoutAttribute.centerY, multiplier: 1.0, constant: 0))
    self.view.addConstraint(NSLayoutConstraint(item: heartImg, attribute: NSLayoutAttribute.height, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1.0, constant: 40))
    self.view.addConstraint(NSLayoutConstraint(item: heartImg, attribute: NSLayoutAttribute.width, relatedBy: NSLayoutRelation.equal, toItem: nil, attribute: NSLayoutAttribute.notAnAttribute, multiplier: 1.0, constant: 40))

Answer 2

您必须使用屏幕 midX 和 midY 属性并减去图像的一半宽度和一半高度：

if let imageURL = NSURL(string:"http://i.stack.imgur.com/Xs4RX.jpg"), data = NSData(contentsOfURL: imageURL), image = UIImage(data: data), image2URL = NSURL(string:"https://graph.facebook.com/10203430834250391/picture?type=large"), data2 = NSData(contentsOfURL: image2URL), image2 = UIImage(data: data2) {

    let imageView = UIImageView(frame: UIScreen.mainScreen().bounds)
    imageView.image = image
    imageView.contentMode = UIViewContentMode.ScaleAspectFit

    let image2View = UIImageView(frame: CGRect(x: UIScreen.mainScreen().bounds.midX-100, y: UIScreen.mainScreen().bounds.midY-100, width: 200, height: 200))
    image2View.image = image2
    image2View.contentMode = UIViewContentMode.Center
    imageView.addSubview(image2View)
    imageView
}

如果您的图像与设备屏幕的尺寸不同，您必须使用较大的图像框架 midX 减去较小的图像框架 midX 并对高度执行相同操作：

 heartImg.frame = CGRectMake(angryBedousImg.frame.size.width / 2, angryBedousImg.frame.size.height / 2, heartImg.frame.size.width, heartImg.frame.size.height)

到

heartImg.frame = CGRectMake(angryBedousImg.frame.midX - heartImg.frame.midX, angryBedousImg.frame.midY - heartImg.frame.midY, heartImg.frame.size.width, heartImg.frame.size.height)