我试图在Swift中使用十六进制颜色值，而不是UIColor允许您使用的少数标准值，但我不知道如何做到这一点。
示例:我如何使用#ffffff作为颜色?
当前回答
我从这个回答中总结了一些想法，并针对iOS 13和Swift 5进行了更新。
extension UIColor {
convenience init(_ hex: String, alpha: CGFloat = 1.0) {
var cString = hex.trimmingCharacters(in: .whitespacesAndNewlines).uppercased()
if cString.hasPrefix("#") { cString.removeFirst() }
if cString.count != 6 {
self.init("ff0000") // return red color for wrong hex input
return
}
var rgbValue: UInt64 = 0
Scanner(string: cString).scanHexInt64(&rgbValue)
self.init(red: CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0,
green: CGFloat((rgbValue & 0x00FF00) >> 8) / 255.0,
blue: CGFloat(rgbValue & 0x0000FF) / 255.0,
alpha: alpha)
}
}
然后你可以这样使用它:
UIColor("#ff0000") // with #
UIColor("ff0000") // without #
UIColor("ff0000", alpha: 0.5) // using optional alpha value
其他回答
这是一个接受十六进制字符串并返回UIColor的函数。 (你可以输入十六进制字符串格式:#ffffff或ffffff)
用法:
var color1 = hexStringToUIColor("#d3d3d3")
Swift 5:(Swift 4+)
func hexStringToUIColor (hex:String) -> UIColor {
var cString:String = hex.trimmingCharacters(in: .whitespacesAndNewlines).uppercased()
if (cString.hasPrefix("#")) {
cString.remove(at: cString.startIndex)
}
if ((cString.count) != 6) {
return UIColor.gray
}
var rgbValue:UInt64 = 0
Scanner(string: cString).scanHexInt64(&rgbValue)
return UIColor(
red: CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0,
green: CGFloat((rgbValue & 0x00FF00) >> 8) / 255.0,
blue: CGFloat(rgbValue & 0x0000FF) / 255.0,
alpha: CGFloat(1.0)
)
}
斯威夫特3:
func hexStringToUIColor (hex:String) -> UIColor {
var cString:String = hex.trimmingCharacters(in: .whitespacesAndNewlines).uppercased()
if (cString.hasPrefix("#")) {
cString.remove(at: cString.startIndex)
}
if ((cString.characters.count) != 6) {
return UIColor.gray
}
var rgbValue:UInt32 = 0
Scanner(string: cString).scanHexInt32(&rgbValue)
return UIColor(
red: CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0,
green: CGFloat((rgbValue & 0x00FF00) >> 8) / 255.0,
blue: CGFloat(rgbValue & 0x0000FF) / 255.0,
alpha: CGFloat(1.0)
)
}
斯威夫特2:
func hexStringToUIColor (hex:String) -> UIColor {
var cString:String = hex.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet() as NSCharacterSet).uppercaseString
if (cString.hasPrefix("#")) {
cString = cString.substringFromIndex(cString.startIndex.advancedBy(1))
}
if ((cString.characters.count) != 6) {
return UIColor.grayColor()
}
var rgbValue:UInt32 = 0
NSScanner(string: cString).scanHexInt(&rgbValue)
return UIColor(
red: CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0,
green: CGFloat((rgbValue & 0x00FF00) >> 8) / 255.0,
blue: CGFloat(rgbValue & 0x0000FF) / 255.0,
alpha: CGFloat(1.0)
)
}
沙德源代码:/ gist: de147c42d7b3063ef7bc
编辑:更新代码。谢谢，Hlung, jaytrixz, Ahmad F, Kegham K和Adam Waite!
我从这个回答中总结了一些想法，并针对iOS 13和Swift 5进行了更新。
extension UIColor {
convenience init(_ hex: String, alpha: CGFloat = 1.0) {
var cString = hex.trimmingCharacters(in: .whitespacesAndNewlines).uppercased()
if cString.hasPrefix("#") { cString.removeFirst() }
if cString.count != 6 {
self.init("ff0000") // return red color for wrong hex input
return
}
var rgbValue: UInt64 = 0
Scanner(string: cString).scanHexInt64(&rgbValue)
self.init(red: CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0,
green: CGFloat((rgbValue & 0x00FF00) >> 8) / 255.0,
blue: CGFloat(rgbValue & 0x0000FF) / 255.0,
alpha: alpha)
}
}
然后你可以这样使用它:
UIColor("#ff0000") // with #
UIColor("ff0000") // without #
UIColor("ff0000", alpha: 0.5) // using optional alpha value
斯威夫特2.3: 用户界面颜色扩展。我认为这样更简单。
extension UIColor {
static func colorFromHex(hexString: String, alpha: CGFloat = 1) -> UIColor {
//checking if hex has 7 characters or not including '#'
if hexString.characters.count < 7 {
return UIColor.whiteColor()
}
//string by removing hash
let hexStringWithoutHash = hexString.substringFromIndex(hexString.startIndex.advancedBy(1))
//I am extracting three parts of hex color Red (first 2 characters), Green (middle 2 characters), Blue (last two characters)
let eachColor = [
hexStringWithoutHash.substringWithRange(hexStringWithoutHash.startIndex...hexStringWithoutHash.startIndex.advancedBy(1)),
hexStringWithoutHash.substringWithRange(hexStringWithoutHash.startIndex.advancedBy(2)...hexStringWithoutHash.startIndex.advancedBy(3)),
hexStringWithoutHash.substringWithRange(hexStringWithoutHash.startIndex.advancedBy(4)...hexStringWithoutHash.startIndex.advancedBy(5))]
let hexForEach = eachColor.map {CGFloat(Int($0, radix: 16) ?? 0)} //radix is base of numeric system you want to convert to, Hexadecimal has base 16
//return the color by making color
return UIColor(red: hexForEach[0] / 255, green: hexForEach[1] / 255, blue: hexForEach[2] / 255, alpha: alpha)
}
}
用法:
let color = UIColor.colorFromHex("#25ac09")
修复了“'scanHexInt32' was deprecated in iOS 13.0”的警告。
示例应该可以在Swift2.2及以上版本(Swift2. exe)上运行。x, Swift3。x, Swift4。x, Swift5.x):
extension UIColor {
// hex sample: 0xf43737
convenience init(_ hex: Int, alpha: Double = 1.0) {
self.init(red: CGFloat((hex >> 16) & 0xFF) / 255.0, green: CGFloat((hex >> 8) & 0xFF) / 255.0, blue: CGFloat((hex) & 0xFF) / 255.0, alpha: CGFloat(255 * alpha) / 255)
}
convenience init(_ hexString: String, alpha: Double = 1.0) {
let hex = hexString.trimmingCharacters(in: CharacterSet.alphanumerics.inverted)
var int = UInt64()
Scanner(string: hex).scanHexInt64(&int)
let r, g, b: UInt64
switch hex.count {
case 3: // RGB (12-bit)
(r, g, b) = ((int >> 8) * 17, (int >> 4 & 0xF) * 17, (int & 0xF) * 17)
case 6: // RGB (24-bit)
(r, g, b) = (int >> 16, int >> 8 & 0xFF, int & 0xFF)
default:
(r, g, b) = (1, 1, 0)
}
self.init(red: CGFloat(r) / 255, green: CGFloat(g) / 255, blue: CGFloat(b) / 255, alpha: CGFloat(255 * alpha) / 255)
}
convenience init(r: CGFloat, g: CGFloat, b: CGFloat, a: CGFloat = 1) {
self.init(red: (r / 255), green: (g / 255), blue: (b / 255), alpha: a)
}
}
像下面这样使用它们:
UIColor(0xF54A45)
UIColor(0xF54A45, alpha: 0.7)
UIColor("#f44")
UIColor("#f44", alpha: 0.7)
UIColor("#F54A45")
UIColor("#F54A45", alpha: 0.7)
UIColor("F54A45")
UIColor("F54A45", alpha: 0.7)
UIColor(r: 245.0, g: 73, b: 69)
UIColor(r: 245.0, g: 73, b: 69, a: 0.7)
斯威夫特5.0
你不能在Swift中直接使用#ffffff语法。以下是我用于网络相关项目的代码。支持alpha和三位数字。
用法示例(大写值也可以):
let hex = "#FADE2B" // yellow
let color = NSColor(fromHex: hex)
支持的字符串格式:
"fff" // RGB "#fff" // #RGB "ffff" // RGBA "#ffff" // #RGBA . "ffffff" // RRGGBB . "#ffffff" // #RRGGBB . "ffffffff" // RRGGBBAA . "#ffffffff" // #RRGGBBAA .
数字代表红色，绿色，蓝色和阿尔法(像透明度)。对于iOS，用UIColor替换NSColor。
代码:
extension NSColor {
/// Initialises NSColor from a hexadecimal string. Color is clear if string is invalid.
/// - Parameter fromHex: supported formats are "#RGB", "#RGBA", "#RRGGBB", "#RRGGBBAA", with or without the # character
public convenience init(fromHex:String) {
var r = 0, g = 0, b = 0, a = 255
let offset = fromHex.hasPrefix("#") ? 1 : 0
let ch = fromHex.map{$0}
switch(ch.count - offset) {
case 8:
a = 16 * (ch[offset+6].hexDigitValue ?? 0) + (ch[offset+7].hexDigitValue ?? 0)
fallthrough
case 6:
r = 16 * (ch[offset+0].hexDigitValue ?? 0) + (ch[offset+1].hexDigitValue ?? 0)
g = 16 * (ch[offset+2].hexDigitValue ?? 0) + (ch[offset+3].hexDigitValue ?? 0)
b = 16 * (ch[offset+4].hexDigitValue ?? 0) + (ch[offset+5].hexDigitValue ?? 0)
break
case 4:
a = 16 * (ch[offset+3].hexDigitValue ?? 0) + (ch[offset+3].hexDigitValue ?? 0)
fallthrough
case 3: // Three digit #0D3 is the same as six digit #00DD33
r = 16 * (ch[offset+0].hexDigitValue ?? 0) + (ch[offset+0].hexDigitValue ?? 0)
g = 16 * (ch[offset+1].hexDigitValue ?? 0) + (ch[offset+1].hexDigitValue ?? 0)
b = 16 * (ch[offset+2].hexDigitValue ?? 0) + (ch[offset+2].hexDigitValue ?? 0)
break
default:
a = 0
break
}
self.init(red: CGFloat(r)/255, green: CGFloat(g)/255, blue: CGFloat(b)/255, alpha: CGFloat(a)/255)
}
}
// Author: Andrew Kingdom
授权:CC BY
我发现这比下面的复制/粘贴更整洁
选择:
您可以删除#并将其存储为32位无符号整数字面量，由0x前缀表示，即0xffffff。不过，你仍然需要代码将其转换为颜色。
如果你想要一种非编程的方式来获取颜色:打开一个颜色选择器对话框，切换到colour Sliders > RGB Sliders，并将值粘贴/输入到“Hex color #”框中。(不要粘贴#散列符号。)
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