针对设置RGB颜色，无需转换

#define DEFAULT_VOID_COLOR [UIColor whiteColor]

+ (UIColor *)colorWithHexString:(NSString *)stringToConvert alpha:(float)alpha

{

    NSString *cString = [[stringToConvertstringByTrimmingCharactersInSet:[NSCharacterSetwhitespaceAndNewlineCharacterSet]]uppercaseString];

    

    if ([cStringlength] <6)

        returnDEFAULT_VOID_COLOR;

    if ([cStringhasPrefix:@"#"])

        cString = [cString substringFromIndex:1];

    if ([cStringlength] !=6)

        returnDEFAULT_VOID_COLOR;

    

    NSRange range;

    range.location =0;

    range.length =2;

    NSString *rString = [cStringsubstringWithRange:range];

    

    range.location =2;

    NSString *gString = [cStringsubstringWithRange:range];

    

    range.location =4;

    NSString *bString = [cStringsubstringWithRange:range];

    

    

    unsignedint r, g, b;

    [[NSScannerscannerWithString:rString]scanHexInt:&r];

    [[NSScannerscannerWithString:gString]scanHexInt:&g];

    [[NSScannerscannerWithString:bString]scanHexInt:&b];

    

    return [UIColorcolorWithRed:((float) r /255.0f)

                           green:((float) g /255.0f)

                            blue:((float) b /255.0f)

                           alpha:alpha];

}