我有一个具有UIColor属性的对象：
class Beer: NSObject {
var color: UIColor?
...
}
我将此保存到数据库中，因此我需要将此属性设置为有效的JSON类型，因此我正在考虑将其转换为字符串。如何转换为要存储的字符串，然后在使用该字符串加载时创建UIColor？
我已经为转换提供了一些示例，但仍然可以找到许多转换代码
对于从UIColor到十六进制字符串的转换，您可以使用以下代码：
extension UIColor {
var rgbComponents:(red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat) {
var r:CGFloat = 0
var g:CGFloat = 0
var b:CGFloat = 0
var a:CGFloat = 0
if getRed(&r, green: &g, blue: &b, alpha: &a) {
return (r,g,b,a)
}
return (0,0,0,0)
}
// hue, saturation, brightness and alpha components from UIColor**
var hsbComponents:(hue: CGFloat, saturation: CGFloat, brightness: CGFloat, alpha: CGFloat) {
var hue:CGFloat = 0
var saturation:CGFloat = 0
var brightness:CGFloat = 0
var alpha:CGFloat = 0
if getHue(&hue, saturation: &saturation, brightness: &brightness, alpha: &alpha){
return (hue,saturation,brightness,alpha)
}
return (0,0,0,0)
}
var htmlRGBColor:String {
return String(format: "#%02x%02x%02x", Int(rgbComponents.red * 255), Int(rgbComponents.green * 255),Int(rgbComponents.blue * 255))
}
var htmlRGBaColor:String {
return String(format: "#%02x%02x%02x%02x", Int(rgbComponents.red * 255), Int(rgbComponents.green * 255),Int(rgbComponents.blue * 255),Int(rgbComponents.alpha * 255) )
}
}
样品用途：
let myColorBlack = UIColor.blackColor().webColor //#000000ff
let myLghtGrayColor = UIColor.lightGrayColor().webColor //#aaaaaaff
let myDarkGrayColor = UIColor.darkGrayColor().webColor
有关更多信息，您可以查看：https://stackoverflow.com/a/28697136/4557505 https://gist.github.com/yannickl/16f0ed38f0698d9a8ae7
您可以将此字符串存储在数据库中，并在需要时检索它
从HexString到UIColor
extension UIColor {
public convenience init?(hexString: String) {
let r, g, b, a: CGFloat
if hexString.hasPrefix("#") {
let start = hexString.startIndex.advancedBy(1)
let hexColor = hexString.substringFromIndex(start)
if hexColor.characters.count == 8 {
let scanner = NSScanner(string: hexColor)
var hexNumber: UInt64 = 0
if scanner.scanHexLongLong(&hexNumber) {
r = CGFloat((hexNumber & 0xff000000) >> 24) / 255
g = CGFloat((hexNumber & 0x00ff0000) >> 16) / 255
b = CGFloat((hexNumber & 0x0000ff00) >> 8) / 255
a = CGFloat(hexNumber & 0x000000ff) / 255
self.init(red: r, green: g, blue: b, alpha: a)
return
}
}
}
return nil
}
}
用法：UIColor（hexString：“＃ffe700ff”）
参考：https://www.hackingwithswift.com/example-code/uicolor/how-to-convert-a-hex-color-to-a-uicolor https://github.com/yeahdongcn/UIColor-Hex-Swift https://gist.github.com/arshad/de147c42d7b3063ef7bc
您可以使用此功能
func returnUIColor(components: String) -> UIColor {
let scanner = Scanner(string: components)
let skipped = CharacterSet(charactersIn: "[], ")
let comma = CharacterSet(charactersIn: ",")
scanner.charactersToBeSkipped = skipped
var r, g, b, a : NSString?
scanner.scanUpToCharacters(from: comma, into: &r)
scanner.scanUpToCharacters(from: comma, into: &g)
scanner.scanUpToCharacters(from: comma, into: &b)
scanner.scanUpToCharacters(from: comma, into: &a)
let defaultColor = UIColor.lightGray
guard let rUnwrapped = r else { return defaultColor }
guard let gUnwrapped = g else { return defaultColor }
guard let bUnwrapped = b else { return defaultColor }
guard let aUnwrapped = a else { return defaultColor }
let rfloat = CGFloat(rUnwrapped.doubleValue)
let gfloat = CGFloat(gUnwrapped.doubleValue)
let bfloat = CGFloat(bUnwrapped.doubleValue)
let afloat = CGFloat(aUnwrapped.doubleValue)
let newUIColor = UIColor(red: rfloat, green: gfloat, blue: bfloat, alpha: afloat)
return newUIColor
}
Swift 3.0 IOS 10.x不明白为什么这么复杂，这个工作......我一定错过了什么......仔细阅读，从第1项开始不是0。
// convert color to string
let color = userInfo["color"] as! UIColor
let diyColor = String(describing: color)
// convert string back to color
let diyValues = diyColor.components(separatedBy: " ")
print("diyValues \(diyValues)")
let returnedColor = UIColor(colorLiteralRed: diyValues[1].FloatValue()!, green: diyValues[2].FloatValue()!, blue: diyValues[3].FloatValue()!, alpha: diyValues[4].FloatValue()!)
也使用这个扩展......
extension String {
func FloatValue() -> Float? {
guard let doubleValue = Double(self) else {
return nil
}
return Float(doubleValue)
}
}
使用下面的UIColor扩展名将String转换为Color，反之亦然。
extension UIColor {
//Convert RGBA String to UIColor object
//"rgbaString" must be separated by space "0.5 0.6 0.7 1.0" 50% of Red 60% of Green 70% of Blue Alpha 100%
public convenience init?(rgbaString : String){
self.init(ciColor: CIColor(string: rgbaString))
}
//Convert UIColor to RGBA String
func toRGBAString()-> String {
var r: CGFloat = 0
var g: CGFloat = 0
var b: CGFloat = 0
var a: CGFloat = 0
self.getRed(&r, green: &g, blue: &b, alpha: &a)
return "\(r) \(g) \(b) \(a)"
}
//return UIColor from Hexadecimal Color string
public convenience init?(hexaDecimalString: String) {
let r, g, b, a: CGFloat
if hexaDecimalString.hasPrefix("#") {
let start = hexaDecimalString.index(hexaDecimalString.startIndex, offsetBy: 1)
let hexColor = hexaDecimalString.substring(from: start)
if hexColor.characters.count == 8 {
let scanner = Scanner(string: hexColor)
var hexNumber: UInt64 = 0
if scanner.scanHexInt64(&hexNumber) {
r = CGFloat((hexNumber & 0xff000000) >> 24) / 255
g = CGFloat((hexNumber & 0x00ff0000) >> 16) / 255
b = CGFloat((hexNumber & 0x0000ff00) >> 8) / 255
a = CGFloat(hexNumber & 0x000000ff) / 255
self.init(red: r, green: g, blue: b, alpha: a)
return
}
}
}
return nil
}
// Convert UIColor to Hexadecimal String
func toHexString() -> String {
var r: CGFloat = 0
var g: CGFloat = 0
var b: CGFloat = 0
var a: CGFloat = 0
self.getRed(&r, green: &g, blue: &b, alpha: &a)
return String(
format: "%02X%02X%02X",
Int(r * 0xff),
Int(g * 0xff),
Int(b * 0xff)
)
}
}
将此颜色字符串（stringWhite）保存到DataBase中
let stringWhite = UIColor.white.toHexString()
当从DataBase读取颜色字符串时，使用下面的代码将stringWhite转换为UIColor
let whiteColor = UIColor(hexaDecimalString: stringWhite)
我添加了自己的扩展，希望你欣赏：
extension UIColor {
func toRGBAString(uppercased: Bool = true) -> String {
var r: CGFloat = 0
var g: CGFloat = 0
var b: CGFloat = 0
var a: CGFloat = 0
self.getRed(&r, green: &g, blue: &b, alpha: &a)
let rgba = [r, g, b, a].map { $0 * 255 }.reduce("", { $0 + String(format: "%02x", Int($1)) })
return uppercased ? rgba.uppercased() : rgba
}
}
受@HardikDG代码的启发，这些是简单的Objective C功能：
- (NSString *) colorToString:(UIColor *) color {
CGFloat red, green, blue, alpha;
[color getRed:&red green:&green blue:&blue alpha:&alpha];
return [NSString stringWithFormat:@"%02x%02x%02x", (int)(red * 255), (int)(green * 255) , (int)(blue * 255)];
}
- (UIColor *) stringToColor:(NSString *) color {
if([color length] != 6) {
return nil;
}
NSScanner *scanner = [NSScanner scannerWithString:color];
UInt64 hexNumber = 0;
if ([scanner scanHexLongLong:&hexNumber]) {
CGFloat r = ((hexNumber & 0xff000000) >> 24) / 255.0;
CGFloat g = ((hexNumber & 0x00ff0000) >> 16) / 255.0;
CGFloat b = ((hexNumber & 0x0000ff00) >> 8) / 255.0;
CGFloat a = (hexNumber & 0x000000ff) / 255.0;
return [UIColor colorWithRed:r green:g blue:b alpha:a];
}
return [UIColor whiteColor];
}
将颜色转换为字符串对象。
let colorJSON: String = UIColor.white.hexValue() //color to string
将字符串转换为颜色对象
view.backgroundColor = UIColor(hexString: colorJSON) //string to respective color