如何使用CGRect以编程方式在父视图中垂直居中UIImage？

Question

I tried to do this one but, the place of the Image changes when I try to run on a different iPhone model in Simulator. I need to do this exactly with CGRect. Thanks in Advance!

    func configure() {
        //MARK: Logo Image
        view.addSubview(logo)
        logo.image = UIImage(named: "cafelogo")
        logo.layer.cornerRadius = 25
        logo.frame = CGRect(x: 100, y: 200, width: 150, height: 150)

Answer 1

You should be using auto-layout constraints -- but first, to show you how to do this with explicit rect / framing:

func configure() {
    //MARK: Logo Image
    view.addSubview(logo)
    logo.image = UIImage(named: "cafelogo")
    logo.layer.cornerRadius = 25
    logo.frame = CGRect(x: 0, y: 0, width: 150, height: 150)
    // center it in the view
    logo.center = view.center
}

but... you have to call this from viewDidLayoutSubviews() . Otherwise, view 's frame has not yet been laid-out:

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    configure()
}

Note that if the frame of view changes - such as on device rotation - your logo image view will no longer be centered. You could add some new code to re-center it, but it is much easier to let auto-layout do all the work.

You can use this code in viewDidLoad() :

    logo.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(logo)
    logo.image = UIImage(named: "cafelogo")
    logo.layer.cornerRadius = 25
    NSLayoutConstraint.activate([
        logo.widthAnchor.constraint(equalToConstant: 150.0),
        logo.heightAnchor.constraint(equalToConstant: 150.0),
        logo.centerXAnchor.constraint(equalTo: view.centerXAnchor),
        logo.centerYAnchor.constraint(equalTo: view.centerYAnchor),
    ])

Now your logo image view is 150x150 and will always remain centered in view .