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Having a problem with UIBarButtonItem resizing when returning to VC with different values for frame and image. 

var selectedR = 1
var leftFrame = CGRect()
var leftImage = UIImage()

override func viewDidLoad() {
    super.viewDidLoad()

    if selectedR == 0
    {
        leftFrame = CGRect(x: 0, y: 0, width: 33, height: 33)
        leftImage = UIImage(named: “pic-0”)!
    }
    else if selectedR == 1
    {
        leftFrame = CGRect(x: 0, y: 0, width: 79, height: 33)
        leftImage = UIImage(named: "pic-1")!
    }
    else if selectedR == 2
    {
        leftFrame =  CGRect(x: 0, y: 0, width: 34, height: 33)
        leftImage = UIImage(named: "pic-2”)!
    }

    let cButton = UIButton(frame: leftFrame)
    cButton.setImage(leftImage, for: UIControlState())
    cButton.addTarget(self.revealViewController(), action: #selector(SWRevealViewController.revealToggle(_:)), for: .touchUpInside)
    cButton.contentMode = UIViewContentMode.scaleAspectFit
    let leftItem = UIBarButtonItem(customView: cButton)
    self.navigationItem.leftBarButtonItem = leftItem
}

First time perfect size for selectedR = 1

Coming back into viewDidLoad with different selectedR value and image blows up, distorts and setting the leftFrame size is not honoured.

This all worked perfect in swift 3, but swift 4 it goes all over the place. Any help or suggestions would be much appreciated.

4

1 回答 1

2

iOS 10 和 11 之间的一个主要变化是现在栏按钮项由自动布局引擎布局。通常这应该是向后兼容的。但是，如果您在布置条形按钮项目时遇到问题，您应该尝试设置约束，看看是否能解决您的问题。

在你的情况下，你会说：

var selectedR = 1
var leftFrame = CGRect()
var leftImage = UIImage()

override func viewDidLoad() {
    super.viewDidLoad()

    if selectedR == 0
    {
        leftFrame = CGRect(x: 0, y: 0, width: 33, height: 33)
        leftImage = UIImage(named: “pic-0”)!
    }
    else if selectedR == 1
    {
        leftFrame = CGRect(x: 0, y: 0, width: 79, height: 33)
        leftImage = UIImage(named: "pic-1")!
    }
    else if selectedR == 2
    {
        leftFrame =  CGRect(x: 0, y: 0, width: 34, height: 33)
        leftImage = UIImage(named: "pic-2”)!
    }

    let cButton = UIButton(frame: leftFrame)
    cButton.widthAnchor.constraint(equalToConstant: leftFrame.width).isActive = true
    cButton.heightAnchor.constraint(equalToConstant: leftFrame.height).isActive = true
    cButton.setImage(leftImage, for: UIControlState())
    cButton.addTarget(self.revealViewController(), action: #selector(SWRevealViewController.revealToggle(_:)), for: .touchUpInside)
    cButton.contentMode = UIViewContentMode.scaleAspectFit
    let leftItem = UIBarButtonItem(customView: cButton)
    self.navigationItem.leftBarButtonItem = leftItem
}

这在 Apple 的 WWDC 2017 会议更新您的 iOS 11 应用程序中有所介绍。

于 2017-09-13T22:37:56.783 回答