iOS 14 UIColorPicker的eyedropper取色工具无法返回选中颜色如何解决

你当前仅实现了UIColorPickerViewControllerDelegate的colorPickerViewControllerDidFinish回调，未满足滴管功能的交互逻辑要求：

• 滴管采样完成后，系统默认触发的是实时选择回调colorPickerViewControllerDidSelectColor:，而非结束回调
• 你每次弹出选择器都新建UIColorPickerViewController实例，未将已选中/采样的颜色赋值给新实例的selectedColor属性，无法实现颜色回填
• 将业务tag存储在vc.view上存在风险，系统内部可能修改视图层级覆盖tag值

1. 新增属性存储选中颜色与业务tag #

先在你的myViewController类中新增以下属性和分类：

// 存储不同业务场景对应的选中颜色，初始值替换为你自己的默认色
private var selectedColors: [Int: UIColor] = [
    1: UIColor.white,
    2: UIColor.lightGray,
    3: UIColor.brown
]
// 给UIColorPickerViewController加关联对象存储业务tag，避免view.tag被覆盖
private var pickerTagKey: UInt8 = 0
extension UIColorPickerViewController {
    var businessTag: Int {
        get { objc_getAssociatedObject(self, &pickerTagKey) as? Int ?? 0 }
        set { objc_setAssociatedObject(self, &pickerTagKey, newValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC) }
    }
}

2. 修改弹出选择器的方法 #

给新建的选择器实例回填上一次选中的颜色：

@objc private func presentColorPicker(tag: Int, sender: UIControl){
    let vc = UIColorPickerViewController()
    vc.supportsAlpha = false
    vc.delegate = self
    vc.businessTag = tag
    vc.selectedColor = selectedColors[tag] ?? .white
    vc.modalPresentationStyle = .popover
    vc.popoverPresentationController?.sourceView = sender
    vc.popoverPresentationController?.sourceRect = sender.bounds
    self.present(vc, animated: true)
}

3. 补充完整代理方法 #

同时实现实时选择回调和结束回调：

extension myViewController: UIColorPickerViewControllerDelegate {
    // 实时选择回调，滴管采样完成后会触发此方法更新选中色
    func colorPickerViewControllerDidSelectColor(_ viewController: UIColorPickerViewController) {
        let tag = viewController.businessTag
        selectedColors[tag] = viewController.selectedColor
    }
  
    func colorPickerViewControllerDidFinish(_ viewController: UIColorPickerViewController) {
        guard let options = editor?.apiView?.getRenderingOptions() else { return }
        let tag = viewController.businessTag
        guard let selectedColor = selectedColors[tag] else { return }
        let newColor = getMobileApiColor(color: selectedColor)
        
        switch tag {
        case 1:
            options.skyColor = newColor
            skyRow.color.backgroundColor = newColor.uiColor
        case 2:
            options.backgroundColor = newColor
            backgroundRow.color.backgroundColor = newColor.uiColor
        case 3:
            options.groundColor = newColor
            groundRow.color.backgroundColor = newColor.uiColor
        default: break
        }
        editor?.modelView?.setNeedsDisplay()
    }
}

内容的提问来源于stack exchange，提问作者Benjamin Morris