将UIColor保存到NSUserDefaults并从NSUserDefaults加载

Posted 2021-03-27

什么是将UIColor保存到NSUserDefaults然后将其退出的最简单方法？

答案

使用the accepted answer，您很快就会在代码中获得大量NSKeyed档案和解压缩。更清洁的解决方案是扩展UserDefaults。这正是扩展的目的; UserDefaults可能不知道UIColor，因为UIKit和Foundation是不同的框架。

Swift

extension UserDefaults {

    func color(forKey key: String) -> UIColor? {
        var color: UIColor?
        if let colorData = data(forKey: key) {
            color = NSKeyedUnarchiver.unarchiveObject(with: colorData) as? UIColor
        }
        return color
    }

    func set(_ value: UIColor?, forKey key: String) {
        var colorData: Data?
        if let color = value {
            colorData = NSKeyedArchiver.archivedData(withRootObject: color)
        }
        set(colorData, forKey: key)
    }

}

Swift 4.2

extension UserDefaults {

    func color(forKey key: String) -> UIColor? {

        guard let colorData = data(forKey: key) else { return nil }

        do {
            return try NSKeyedUnarchiver.unarchivedObject(ofClass: UIColor.self, from: colorData)
        } catch let error {
            print("color error (error.localizedDescription)")
            return nil
        }

    }

    func set(_ value: UIColor?, forKey key: String) {

        guard let color = value else { return }
        do {
            let data = try NSKeyedArchiver.archivedData(withRootObject: color, requiringSecureCoding: false)
            set(data, forKey: key)
        } catch let error {
            print("error color key data not saved (error.localizedDescription)")
        }

    }

}

Usage

UserDefaults.standard.set(UIColor.white, forKey: "white")
let whiteColor = UserDefaults.standard.color(forKey: "white")

这也可以在具有类别的Objective-C中完成。

我已经将Swift文件添加为gist here。

另一答案

这样做的一种方法可能是归档它（就像使用NSColor，虽然我没有测试过这个）：

NSData *colorData = [NSKeyedArchiver archivedDataWithRootObject:color];
[[NSUserDefaults standardUserDefaults] setObject:colorData forKey:@"myColor"];

并把它拿回来：

NSData *colorData = [[NSUserDefaults standardUserDefaults] objectForKey:@"myColor"];
UIColor *color = [NSKeyedUnarchiver unarchiveObjectWithData:colorData];

另一答案

我自己得到了答案

保存

const CGFloat  *components = CGColorGetComponents(pColor.CGColor);
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
[prefs setFloat:components[0]  forKey:@"cr"];
[prefs setFloat:components[1]  forKey:@"cg"];
[prefs setFloat:components[2]  forKey:@"cb"];
[prefs setFloat:components[3]  forKey:@"ca"];

加载

NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
UIColor* tColor = [UIColor colorWithRed:[prefs floatForKey:@"cr"] green:[prefs floatForKey:@"cg"] blue:[prefs floatForKey:@"cb"] alpha:[prefs floatForKey:@"ca"]];

另一答案

感谢Erica's UIColor category。我不喜欢在首选项中保存4个浮点数，只想要一个条目。

因此，使用Erica的UIColor类别，我能够将RGB颜色转换为/可以保存在首选项中的NSString。

// Save a color
NSString *theColorStr = [self.artistColor stringFromColor];
[[NSUserDefaults standardUserDefaults] setObject:theColorStr forKey:@"myColor"];

// Read a color
NSString *theColorStr = [[NSUserDefaults standardUserDefaults] objectForKey:@"myColor"];
if ([theColorStr length] > 0) {
    self.myColor = [UIColor colorWithString:theColorStr];
} else {
    self.myColor = [UIColor colorWithRed:88.0/255.0 green:151.0/255.0 blue:237.0/255.0 alpha:1.0];
}

另一答案

Swift 3, UserDefaults Extension

extension UserDefaults {

    internal func color(forKey key: String) -> UIColor? {
        guard let colorData = data(forKey: key) else {
            return nil
        }

        return NSKeyedUnarchiver.unarchiveObject(with: colorData) as? UIColor
    }

    internal func setColor(_ color: UIColor?, forKey key: String) {
        let colorData: Data?
        if let color = color {
            colorData = NSKeyedArchiver.archivedData(withRootObject: color)
        }
        else {
            colorData = nil
        }

        set(colorData, forKey: key)
    }
}

示例使用

let colorKey = "favoriteColor"

UserDefaults.standard.setColor(UIColor.red, forKey: colorKey)
let favoriteColor = UserDefaults.standard.color(forKey: colorKey)

print("favoriteColor is red: '(favoriteColor == UIColor.red)'")

这个答案是基于a previous answer。它更新为Swift 3。

另一答案

我需要在用户默认值中存储UIColor对象的数组。如其他答案所述，Idea是将UIColor转换为Data并保存该数据。我在UIColor上做了扩展：

extension UIColor {
   func data() -> Data {
      return NSKeyedArchiver.archivedData(withRootObject: self)
   }
   class func color(withData data: Data) -> UIColor? {
      return NSKeyedUnarchiver.unarchiveObject(with: data) as? UIColor
   }
}

用法：

fileprivate var savedColors: [UIColor]? {
    get {
        if let colorDataArray = UserDefaults.standard.array(forKey: Constants.savedColorsKey) as? [Data] {
            return colorDataArray.map { UIColor.color(withData: $0)! }
        }
        return nil
    }
    set {
        if let colorDataArray = newValue?.map({ $0.data() }) {
            UserDefaults.standard.set(colorDataArray, forKey: Constants.savedColorsKey)
        }

    }
}

另一答案

迅速

private let colorPickerKey = "ColorPickerKey"

var selectedColor: UIColor? {
    get {
        guard let colorData = UserDefaults.standard.object(forKey: colorPickerKey) as? Data,
            let color = NSKeyedUnarchiver.unarchiveObject(with: colorData) as? UIColor else { return nil }
        return color
    } set {
        guard let newValue = newValue else {
            UserDefaults.standard.removeObject(forKey: colorPickerKey)
            return
        }
        let colorData = NSKeyedArchiver.archivedData(withRootObject: newValue)
        UserDefaults.standard.set(colorData, forKey: colorPickerKey)
    }
}

另一答案

编辑2：我似乎找到了answer。查看Erica Sadun关于扩展UIColor的文章。

编辑：此代码似乎不适用于UIColor对象。不知道为什么......

以下是一些代码：

将对象保存到NSUserDefaults：

 NSUserDefaults *userDefaults =[NSUserDefaults standardUserDefaults];
[userDefaults setObject:someColorObject forKey:@"myColor"];

从NSUserDefaults读取对象：

NSUserDefaults *userDefaults =[NSUserDefaults standardUserDefaults];
UIColor *someColor = (UIColor *)[userDefaults objectForKey:@"myColor"];