iOS UIColor RGB HEX

+(UIColor *)colorWithR:(CGFloat)r g:(CGFloat)g b:(CGFloat)b a:(CGFloat)a{

    return [UIColor colorWithRed:r/255.0f green:g/255.0f blue:b/255.0f alpha:a/100.0f];

}

+ (UIColor *)colorWithHexString:(NSString *)colorStr alpha:(CGFloat)alpha {

    //移除前缀

    if ([colorStr hasPrefix:@"0X"] || [colorStr hasPrefix:@"0x"]) {

        colorStr = [colorStr substringFromIndex:];

    }

    if ([colorStr hasPrefix:@"#"]) {

        colorStr = [colorStr substringFromIndex:];

    }

    //判断长度

    if (colorStr.length != ) {

        return [UIColor clearColor];

    }

    //提取值

    NSRange range;

    range.length = ;

    //r

    range.location = ;

    NSString *rStr = [colorStr substringWithRange:range];

    //g

    range.location = ;

    NSString *gStr = [colorStr substringWithRange:range];

    //b

    range.location = ;

    NSString *bStr = [colorStr substringWithRange:range];

    //转换值

    unsigned int r, g, b;

    [[NSScanner scannerWithString:rStr] scanHexInt:&r];

    [[NSScanner scannerWithString:gStr] scanHexInt:&g];

    [[NSScanner scannerWithString:bStr] scanHexInt:&b];

    return [UIColor colorWithRed:(r/255.0f) green:(g/255.0f) blue:(b/255.0f) alpha:alpha];

}