问题描述
我需要让标签的 center.x
直接与 tabBar 的 imageView 中的图像对齐。使用下面的代码,标签未对齐,而不是标签的文本“123”直接位于 tabBar 内的铃铛上方,而是在右侧。
guard let keyWindow = UIApplication.shared.windows.first(where: { $0.isKeyWindow }) else { return }
guard let fourthTab = tabBarController?.tabBar.items?[3].value(forKey: "view") as? UIView else { return }
guard let imageView = fourthTab.subviews.compactMap({ $0 as? UIImageView }).first else { return }
guard let imageViewRectInWindow = imageView.superview?.superview?.convert(fourthTab.frame,to: keyWindow) else { return }
let imageRect = AVMakeRect(aspectRatio: imageView.image!.size,insideRect: imageViewRectInWindow)
myLabel.text = "123"
myLabel.textAlignment = .center // I also tried .left
myLabel.center.x = imageRect.midX
myLabel.center.y = UIScreen.main.bounds.height - 74
myLabel.frame.size.width = 50
myLabel.frame.size.height = 21
print("imageViewRectInWindow: \(imageViewRectInWindow)") // (249.99999999403948,688.0,79.00000000298022,48.0)
print("imageRect: \(imageRect)") // (265.4999999955296,48.0,48.0)
print("myLabelRect: \(myLabel.frame)") // (289.4999999955296,662.0,50.0,21.0)
解决方法
这可能是布局问题,例如,在布局所有内容之前设置坐标。你从哪里调用代码?我能够让它与以下一起工作,但是如果您使用某些功能,则会得到奇怪的结果,因此请删除其中的几个。使用 tabview 的框架对我有用,并从视图控制器的 viewDidLayoutSubviews 函数调用坐标设置。
class ViewController: UIViewController {
var myLabel: UILabel = UILabel()
var secondTab: UIView?
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
self.view.addSubview(myLabel)
myLabel.textColor = .black
myLabel.text = "123"
myLabel.textAlignment = .center // I also tried .left
myLabel.frame.size.width = 50
myLabel.frame.size.height = 21
secondTab = tabBarController?.tabBar.items?[1].value(forKey: "view") as? UIView
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
guard let secondTab = secondTab else {
return
}
myLabel.center.x = secondTab.frame.midX
myLabel.center.y = UIScreen.main.bounds.height - 70
}
}
,
试试下面的代码,通过标签栏项目索引返回一个 centerX。
extension UIViewController {
func centerX(of tabItemIndex: Int) -> CGFloat? {
guard let tabBarItemCount = tabBarController?.tabBar.items?.count else { return nil }
let itemWidth = view.bounds.width / CGFloat(tabBarItemCount)
return itemWidth * CGFloat(tabItemIndex + 1) - itemWidth / 2
}
}