我如何从十六进制字符串格式创建一个UIColor,如#00FF00?
当前回答
extension UIColor
{
class func fromHexaString(hex:String) -> UIColor
{
let scanner = Scanner(string: hex)
scanner.scanLocation = 0
var rgbValue: UInt64 = 0
scanner.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)
)
}
}
//you can call like this.
UIColor.fromHexaString(hex:3276b1)
其他回答
一个伟大的Swift实现(为Xcode 7更新)使用扩展,从各种不同的答案和地方拉到一起。在结尾还需要字符串扩展名。
Use:
let hexColor = UIColor(hex: "#00FF00")
注意:我添加了一个选项,为alpha通道的标准6位十六进制值的末尾添加2个额外的数字(传入值为00-99)。如果这冒犯了你,就把它拿掉。您可以实现它来传递一个可选的alpha参数。
扩展:
extension UIColor {
convenience init(var hex: String) {
var alpha: Float = 100
let hexLength = hex.characters.count
if !(hexLength == 7 || hexLength == 9) {
// A hex must be either 7 or 9 characters (#RRGGBBAA)
print("improper call to 'colorFromHex', hex length must be 7 or 9 chars (#GGRRBBAA)")
self.init(white: 0, alpha: 1)
return
}
if hexLength == 9 {
// Note: this uses String subscripts as given below
alpha = hex[7...8].floatValue
hex = hex[0...6]
}
// Establishing the rgb color
var rgb: UInt32 = 0
let s: NSScanner = NSScanner(string: hex)
// Setting the scan location to ignore the leading `#`
s.scanLocation = 1
// Scanning the int into the rgb colors
s.scanHexInt(&rgb)
// Creating the UIColor from hex int
self.init(
red: CGFloat((rgb & 0xFF0000) >> 16) / 255.0,
green: CGFloat((rgb & 0x00FF00) >> 8) / 255.0,
blue: CGFloat(rgb & 0x0000FF) / 255.0,
alpha: CGFloat(alpha / 100)
)
}
}
字符串扩展: 浮动的来源 下标源
extension String {
/**
Returns the float value of a string
*/
var floatValue: Float {
return (self as NSString).floatValue
}
/**
Subscript to allow for quick String substrings ["Hello"][0...1] = "He"
*/
subscript (r: Range<Int>) -> String {
get {
let start = self.startIndex.advancedBy(r.startIndex)
let end = self.startIndex.advancedBy(r.endIndex - 1)
return self.substringWithRange(start..<end)
}
}
}
另一个带有alpha的版本
#define UIColorFromRGBA(rgbValue) [UIColor colorWithRed:((float)((rgbValue & 0xFF000000) >> 24))/255.0 green:((float)((rgbValue & 0xFF0000) >> 16))/255.0 blue:((float)((rgbValue & 0xFF00) >> 8 ))/255.0 alpha:((float)((rgbValue & 0xFF))/255.0)]
swift 2.0+。 这段代码对我来说很好。
extension UIColor {
/// UIColor(hexString: "#cc0000")
internal convenience init?(hexString:String) {
guard hexString.characters[hexString.startIndex] == Character("#") else {
return nil
}
guard hexString.characters.count == "#000000".characters.count else {
return nil
}
let digits = hexString.substringFromIndex(hexString.startIndex.advancedBy(1))
guard Int(digits,radix:16) != nil else{
return nil
}
let red = digits.substringToIndex(digits.startIndex.advancedBy(2))
let green = digits.substringWithRange(Range<String.Index>(start: digits.startIndex.advancedBy(2),
end: digits.startIndex.advancedBy(4)))
let blue = digits.substringWithRange(Range<String.Index>(start:digits.startIndex.advancedBy(4),
end:digits.startIndex.advancedBy(6)))
let redf = CGFloat(Double(Int(red, radix:16)!) / 255.0)
let greenf = CGFloat(Double(Int(green, radix:16)!) / 255.0)
let bluef = CGFloat(Double(Int(blue, radix:16)!) / 255.0)
self.init(red: redf, green: greenf, blue: bluef, alpha: CGFloat(1.0))
}
}
此代码包括字符串格式检查。 如。
let aColor = UIColor(hexString: "#dadada")!
let failed = UIColor(hexString: "123zzzz")
据我所知,我的代码在维护可失败条件的语义和返回可选值方面没有任何缺点。这应该是最好的答案。
斯威夫特版本:
extension UIColor {
convenience init?(var hex: String) {
hex = hex.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet()).uppercaseString
hex = (hex.hasPrefix("#")) ? hex.substringFromIndex(advance(hex.startIndex, 1)) : hex
var value: UInt32 = 0
if NSScanner(string: hex).scanHexInt(&value) {
if count(hex) == 8 {
self.init(red: CGFloat((value & 0xFF000000) >> 24) / 255.0,
green: CGFloat((value & 0x00FF0000) >> 16) / 255.0,
blue: CGFloat((value & 0x0000FF00) >> 8) / 255.0,
alpha: CGFloat((value & 0x000000FF)) / 255.0)
return
} else if count(hex) == 6 {
self.init(red: CGFloat((value & 0xFF0000) >> 16) / 255.0,
green: CGFloat((value & 0x00FF00) >> 8) / 255.0,
blue: CGFloat(value & 0x0000FF) / 255.0,
alpha: 1.0)
return
}
}
self.init()
return nil
}
}
斯威夫特2.0:
将此方法添加到VC或扩展UIColor。
func colorWithHexString (hex:String) -> UIColor {
var cString:String = hex.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet()).uppercaseString
if (cString.hasPrefix("#")) {
cString = (cString as NSString).substringFromIndex(1)
}
if (cString.characters.count != 6) {
return UIColor.grayColor()
}
let rString = (cString as NSString).substringToIndex(2)
let gString = ((cString as NSString).substringFromIndex(2) as NSString).substringToIndex(2)
let bString = ((cString as NSString).substringFromIndex(4) as NSString).substringToIndex(2)
var r:CUnsignedInt = 0, g:CUnsignedInt = 0, b:CUnsignedInt = 0;
NSScanner(string: rString).scanHexInt(&r)
NSScanner(string: gString).scanHexInt(&g)
NSScanner(string: bString).scanHexInt(&b)
return UIColor(red: CGFloat(r) / 255.0, green: CGFloat(g) / 255.0, blue: CGFloat(b) / 255.0, alpha: CGFloat(1))
}
用法:
loginButton.tintColor = self.colorWithHexString("#be1337")
OR
let hexColor = self.colorWithHexString("#be1337")
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