ios - UIbutton 的图像没有改变

Question

我制作了一个面包屑导航，显示您选择的每个单元格的标题。对于第一个屏幕 - 在选择单元格之前，我想显示一个主页图标。选择一个单元格后，我想更改图标。

let button = UIButton(frame: CGRect(x: 0, y: 0, width: 44, height: 44))
        breadcrumbsTitles.count <= 1 ? button.setImage(UIImage(named: "home_1x"), for: .normal) : button.setImage(UIImage(named: "arrow_left"), for: .normal)
        button.addTarget(self, action: #selector(backPressed), for: .touchUpInside)

//container for the bread crumb navigation 
container.addSubview(button)

<小时/>

breadcrumbsTitles 包含我的容器中的所有单元格/ View :

public var breadcrumbsTitles: [String] {
        return self.viewControllers.map {
            $0.title ?? ""
        }
    }

<小时/>

breadcrumbsTitles.count

返回面包屑导航中的标题数量。为什么当选择一个单元格时我的按钮没有改变其图像？我还尝试使用 if-else 语句，但它也不起作用:

if breadcrumbsTitles.count <= 1{
button.setImage(UIImage(named: "home_1x"), for: .normal)
} else ... // set image to "arrow_left"

为什么在我选择单元格或其他内容后，按钮的图像没有改变？

Answer 1

Your container is not ready to add more addSubview view first you can correct container view then working fine.

1. 我在 viewDidLoad 中添加工作正常

导入UIKit

class ViewController: UIViewController {

    let breadcrumbsTitles = ["1","2","3"]

    override func viewDidLoad() {
        super.viewDidLoad()

        let button = UIButton(frame: CGRect(x: 0, y: 0, width: 44, height: 44))
        breadcrumbsTitles.count <= 1 ? button.setImage(UIImage(named: "default"), for: .normal) : button.setImage(UIImage(named: "arrow_left"), for: .normal)
        button.addTarget(self, action: #selector(btnPress), for: .touchUpInside)
        button.backgroundColor = UIColor.red
        self.view.addSubview(button)

    }


    @objc func btnPress() {


    }


}