（iOS开发）根据字符串中的数值取出颜色

最新推荐文章于 2024-02-04 14:58:50 发布

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本文介绍了一种将十六进制颜色字符串转换为UIColor对象的方法。通过解析颜色字符串，将其拆分为红、绿、蓝三个部分，并使用NSScanner进行16进制扫描，最终创建并返回对应的UIColor对象。

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-(UIColor *)getColorFromString:(NSString *)colorString
{
    int colorInt=[colorString intValue];
    if(colorInt<0)
        return [UIColor whiteColor];
    NSString *nLetterValue;
    NSString *colorString16 =@"";
    int ttmpig;
    for (int i = 0; i<9; i++)
    {
        ttmpig=colorInt%16;
        colorInt=colorInt/16;
        switch (ttmpig)
        {
            case 10:
                nLetterValue =@"A";break;
            case 11:
                nLetterValue =@"B";break;
            case 12:
                nLetterValue =@"C";break;
            case 13:
                nLetterValue =@"D";break;
            case 14:
                nLetterValue =@"E";break;
            case 15:
                nLetterValue =@"F";break;
            default:
                nLetterValue=[[NSString alloc]initWithFormat:@"%i",ttmpig];
        }
        colorString16 = [nLetterValue stringByAppendingString:colorString16];
        if (colorInt == 0)
            break;
    }
    colorString16 = [[colorString16 stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];
    //去掉前后空格换行符
    // strip 0X if it appears
    if ([colorString16 hasPrefix:@"0X"])
        colorString16 = [colorString16 substringFromIndex:2];
    if ([colorString16 hasPrefix:@"#"])
        colorString16 = [colorString16 substringFromIndex:1];
    // String should be 6 or 8 characters
    if ([colorString16 length] < 6)
    {
        int cc=6-[colorString16 length];
        for (int i=0; i<cc; i++)
            colorString16=[@"0" stringByAppendingString:colorString16];
    }
    if ([colorString16 length] != 6)
        return [UIColor whiteColor];        // Separate into r, g, b substrings
    NSRange range;
    range.location = 0;
    range.length = 2;
    NSString *bString = [colorString16 substringWithRange:range];
    range.location = 2;
    NSString *gString = [colorString16 substringWithRange:range];
    range.location = 4;
    NSString *rString = [colorString16 substringWithRange:range];
    // Scan values
    unsigned int r, g, b;
    [[NSScanner scannerWithString:rString] scanHexInt:&r];
    //扫描16进制到int
    [[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];
}