我如何从十六进制字符串格式创建一个UIColor,如#00FF00?
当前回答
我为它创建了一个便利的init:
extension UIColor {
convenience init(hex: String, alpha: CGFloat)
{
let redH = CGFloat(strtoul(hex.substringToIndex(advance(hex.startIndex,2)), nil, 16))
let greenH = CGFloat(strtoul(hex.substringWithRange(Range<String.Index>(start: advance(hex.startIndex, 2), end: advance(hex.startIndex, 4))), nil, 16))
let blueH = CGFloat(strtoul(hex.substringFromIndex(advance(hex.startIndex,4)), nil, 16))
self.init(red: redH/255, green: greenH/255, blue: blueH/255, alpha: alpha)
}
}
然后你可以在项目的任何地方创建一个UIColor,就像这样:
UIColor(hex: "ffe3c8", alpha: 1)
希望这对你有所帮助……
其他回答
大多数发布的解决方案使用了Scanner,但至少在现代Swift中你并不真正需要它。相反,你可以简单地使用UInt init和基数16,然后使用基本的二进制操作来获得UIColor组件:
func stringToColor(color: String) -> UIColor {
guard let i = UInt(color, radix: 16) else {
return UIColor.white
}
return UIColor(
red: CGFloat((i & 0xFF0000) >> 16) / 255.0,
green: CGFloat((i & 0xFF00) >> 8) / 255.0,
blue: CGFloat(i & 0xFF) / 255.0,
alpha: 1.0
)
}
这个解决方案期望输入像“FF00FF”,你可能需要删除前面的哈希符号(#),如果你的字符串中有一个。
试试这个:这段代码将从十六进制颜色字符串返回UIColor
- (UIColor*)colorWithHexString:(NSString*)hex
{
NSString *cString = [[hex stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];
// String should be 6 or 8 characters
if ([cString length] < 6) return [UIColor grayColor];
// strip 0X if it appears
if ([cString hasPrefix:@"0X"]) cString = [cString substringFromIndex:2];
if ([cString length] != 6) return [UIColor grayColor];
// Separate into r, g, b substrings
NSRange range;
range.location = 0;
range.length = 2;
NSString *rString = [cString substringWithRange:range];
range.location = 2;
NSString *gString = [cString substringWithRange:range];
range.location = 4;
NSString *bString = [cString substringWithRange:range];
// Scan values
unsigned int r, g, b;
[[NSScanner scannerWithString:rString] scanHexInt:&r];
[[NSScanner scannerWithString:gString] scanHexInt:&g];
[[NSScanner scannerWithString:bString] scanHexInt:&b];
return [UIColor colorWithRed:((float) r / 255.0f)
green:((float) g / 255.0f)
blue:((float) b / 255.0f)
alpha:1.0f];
}
伊森·斯特里德回答的简单例子。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)
例子:
func hexStringToUIColor (hex:String) -> UIColor {
var cString: String = hex.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines).uppercased()
if (cString.hasPrefix("#")) {
if let range = cString.range(of: cString) {
cString = cString.substring(from: cString.index(range.lowerBound, offsetBy: 1))
}
}
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)
)
}
用法:
var color1 = hexStringToUIColor("#d3d3d3")
Swift 2.0 - Xcode 7.2
为UIColor添加扩展。
文件-新建- Swift文件-命名。添加以下内容。
extension UIColor {
convenience init(hexString:String) {
let hexString:NSString = hexString.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
let scanner = NSScanner(string: hexString as String)
if (hexString.hasPrefix("#")) {
scanner.scanLocation = 1
}
var color:UInt32 = 0
scanner.scanHexInt(&color)
let mask = 0x000000FF
let r = Int(color >> 16) & mask
let g = Int(color >> 8) & mask
let b = Int(color) & mask
let red = CGFloat(r) / 255.0
let green = CGFloat(g) / 255.0
let blue = CGFloat(b) / 255.0
self.init(red:red, green:green, blue:blue, alpha:1)
}
func toHexString() -> String {
var r:CGFloat = 0
var g:CGFloat = 0
var b:CGFloat = 0
var a:CGFloat = 0
getRed(&r, green: &g, blue: &b, alpha: &a)
let rgb:Int = (Int)(r*255)<<16 | (Int)(g*255)<<8 | (Int)(b*255)<<0
return NSString(format:"#%06x", rgb) as String
}
}
用法:
Ex. Setting Button's color from hexCode.
override func viewWillAppear(animated: Bool) {
loginButton.tintColor = UIColor(hexString: " hex code here ")
}
Ex. Converting Button's current color to hex Code.
override func viewWillAppear(animated: Bool) {
let hexString = loginButton.tintColor.toHexString()
print("HEX STRING: \(hexString)")
}
你可以使用这个库
https://github.com/burhanuddin353/TFTColor
斯威夫特
UIColor.colorWithRGB(hexString: "FF34AE" alpha: 1.0)
objective - c
[UIColor colorWithRGBHexString:@"FF34AE" alpha:1.0f]
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