Ios Swift 3新更新。为什么我的导航标题是更新前的两倍？

我有一个图像设置为导航栏标题的应用程序。我有一个完美的尺寸，但自从我更新了我的iPhone和mac/xcode后，图像是图像的实际大小，而不是设置的大小。我该如何解决这个问题？谢谢

var titleView : UIImageView

titleView = UIImageView(frame: CGRect(x: 0, y: 0, width: 32, height: 32))

titleView.contentMode = .scaleAspectFit

titleView.image = UIImage(named: "logo.png")

self.navigationItem.titleView = titleView

请像这样使用：

var titleView : UIImageView

titleView = UIImageView(frame: CGRect(x: 0, y: 0, width: 32, height: 32))
let widthConstraint = titleView.widthAnchor.constraint(equalToConstant: 32)
let heightConstraint = titleView.heightAnchor.constraint(equalToConstant: 32)
heightConstraint.isActive = true
widthConstraint.isActive = true

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要添加稍微不同的操作方法，请执行以下操作：

使用autolayout时，不值得设置视图的框架，因为它们将在布局过程中被覆盖，所以我会这样做，添加注释以解释我的操作：

// Unless you are going to recreate the view, just use a let not a var.
// A UIImageView is a reference type, so you can still change the image to be displayed.
// Also, there is no point declaring a variable and then setting it on the next line, just do it all at once.
// Using the non-parameterised initialiser uses a zero frame for the rect.
let titleView = UIImageView()

// Since the view is being created in code and autolayout is going to be applied, you need to add this line to prevent layout conflicts.
titleView.translatesAutoresizingMaskIntoConstraints = false

// Configure the aspect ratio of the displayed image.
titleView.contentMode = .scaleAspectFit

// You don't need to keep a reference to the constraint unless you want to activate and deactivate it.
titleView.widthAnchor.constraint(equalToConstant: 32).isActive = true

// Now, since you want the image to be a square, you can create an layout anchor that specifies this requirement, rather than just duplicating the width value.
titleView.heightAnchor.constraint(equalTo: titleView.widthAnchor, multiplier: 1).isActive = true

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完美的非常感谢。只是需要调整尺寸。