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如何在objective-c中将RGB十六进制字符串转换为UIColor？

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13

我有来自url数据的颜色值就像这样，“＃ff33cc” . 如何将此值转换为UIColor？我正在尝试使用以下代码行 . 我没有得到baseColor1的值 . 看起来我应该把那个捣蛋 . 还有另一种方法吗？

NSScanner *scanner2 = [NSScanner scannerWithString:@"#ff33cc"];
int baseColor1;
[scanner2 scanHexInt:&baseColor1]; 
CGFloat red = (baseColor1 & 0xFF0000);
[UIColor colorWithRed:red ...
objective-c rgb

5 回答

  • 25

    你很接近，但是colorWithRed:green:blue:alpha:期望值从0.0到1.0，所以你需要向右移位并除以255.0f：

    CGFloat red   = ((baseColor1 & 0xFF0000) >> 16) / 255.0f;
CGFloat green = ((baseColor1 & 0x00FF00) >>  8) / 255.0f;
CGFloat blue  =  (baseColor1 & 0x0000FF) / 255.0f;

    EDIT - 另外NSScanner 's scanHexInt will skip past 0x in front of a hex string, but I don' t认为它将跳过十六进制字符串前面的＃字符 . 您可以添加此行来处理：

    [scanner2 setCharactersToBeSkipped:[NSCharacterSet symbolCharacterSet]];
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  • 0

    我添加了一个字符串替换，因此它接受带有或不带 # 的十六进制字符串

    可能的完整代码：

    + (UIColor *)colorWithHexString:(NSString *)stringToConvert
{
    NSString *noHashString = [stringToConvert stringByReplacingOccurrencesOfString:@"#" withString:@""]; // remove the #
    NSScanner *scanner = [NSScanner scannerWithString:noHashString];
    [scanner setCharactersToBeSkipped:[NSCharacterSet symbolCharacterSet]]; // remove + and $

    unsigned hex;
    if (![scanner scanHexInt:&hex]) return nil;
    int r = (hex >> 16) & 0xFF;
    int g = (hex >> 8) & 0xFF;
    int b = (hex) & 0xFF;

    return [UIColor colorWithRed:r / 255.0f green:g / 255.0f blue:b / 255.0f alpha:1.0f];
}
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  • 0

    我已经创建了一个在以下情况下工作的函数： - 1）有或没有＃2）3和6个字符的长值＃000以及＃000000 3）如果额外的数字超过6，它会忽略额外的数字

    //Function Call
UIColor *organizationColor = [self colorWithHexString:@"#AAAAAAAAAAAAA" alpha:1];

//Function
- (UIColor *)colorWithHexString:(NSString *)str_HEX  alpha:(CGFloat)alpha_range{
    NSString *noHashString = [str_HEX stringByReplacingOccurrencesOfString:@"#" withString:@""]; // remove the #

    int red = 0;
    int green = 0;
    int blue = 0;

if ([str_HEX length]<=3)
    {
        sscanf([noHashString UTF8String], "%01X%01X%01X", &red, &green, &blue);
        return  [UIColor colorWithRed:red/16.0 green:green/16.0 blue:blue/16.0 alpha:alpha_range];
    }
else if ([str_HEX length]>7)
    {
        NSString *mySmallerString = [noHashString substringToIndex:6];
        sscanf([mySmallerString UTF8String], "%02X%02X%02X", &red, &green, &blue);
        return  [UIColor colorWithRed:red/255.0 green:green/255.0 blue:blue/255.0 alpha:alpha_range];
    }
else
{
    sscanf([noHashString UTF8String], "%02X%02X%02X", &red, &green, &blue);
    return  [UIColor colorWithRed:red/255.0 green:green/255.0 blue:blue/255.0 alpha:alpha_range];
}}
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  • 12

    请参考此链接将十六进制字符串转换为目标c代码

    http://www.touch-code-magazine.com/web-color-to-uicolor-convertor

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  • 1

    Swift

    这非常有用

    extension UIColor {

    convenience init(hexString: String) {
        let hex = hexString.trimmingCharacters(in: CharacterSet.alphanumerics.inverted)
        var int = UInt32()
        Scanner(string: hex).scanHexInt32(&int)
        let a, r, g, b: UInt32
        switch hex.count {
        case 3: // RGB (12-bit)
            (a, r, g, b) = (255, (int >> 8) * 17, (int >> 4 & 0xF) * 17, (int & 0xF) * 17)
        case 6: // RGB (24-bit)
            (a, r, g, b) = (255, int >> 16, int >> 8 & 0xFF, int & 0xFF)
        case 8: // ARGB (32-bit)
            (a, r, g, b) = (int >> 24, int >> 16 & 0xFF, int >> 8 & 0xFF, int & 0xFF)
        default:
            (a, r, g, b) = (1, 1, 1, 0)
        }
        self.init(red: CGFloat(r) / 255, green: CGFloat(g) / 255, blue: CGFloat(b) / 255, alpha: CGFloat(a) / 255)
    }

    public func hexStringWithAlpha(_ includeAlpha: Bool) -> 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)

        if (includeAlpha) {
            return String(format: "%02X%02X%02X%02X", Int(r * 255), Int(g * 255), Int(b * 255), Int(a * 255))
        } else {
            return String(format: "%02X%02X%02X", Int(r * 255), Int(g * 255), Int(b * 255))
        }
    }

    open override var description: String {
        return self.hexStringWithAlpha(true)
    }

    open override var debugDescription: String {
        return self.hexStringWithAlpha(true)
    }
}

    Obj-C

    UIColor *organizationColor = [self colorWithHexString:@"#ababab" alpha:1];


- (UIColor *)colorWithHexString:(NSString *)str_HEX  alpha:(CGFloat)alpha_range{
    int red = 0;
    int green = 0;
    int blue = 0;
    sscanf([str_HEX UTF8String], "#%02X%02X%02X", &red, &green, &blue);
    return  [UIColor colorWithRed:red/255.0 green:green/255.0 blue:blue/255.0 alpha:alpha_range];
}
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