iOS-十六进制颜色转换 0xFFFFFFFF

• 十六进制颜色转换

当颜色值大于6位时，例如：0xFFFFFFFF, 取前两位为alpha值，

- (UIColor *)yxHandleStrToColor {
    if (self) {
        UIColor *color = [UIColor colorFromHexString_au:self alpha:1];
        
        NSString *tmpColorStr = @"";
        if ([self hasPrefix:@"#"]) {
            tmpColorStr = [self stringByReplacingOccurrencesOfString:@"#" withString:@""];
        }else if ([self hasPrefix:@"0x"]) {
            tmpColorStr = [self stringByReplacingOccurrencesOfString:@"0x" withString:@""];
        }else {
            tmpColorStr = self ?:@"";
        }
        if (tmpColorStr.length > 6) {
            NSString *alphaStr = [self substringToIndex:2];
            long colorLong = strtoul([alphaStr cStringUsingEncoding:NSUTF8StringEncoding], 0, 16);
            CGFloat yxAlpha = 1;
            yxAlpha = (float)colorLong /255.0f;
            color = [UIColor colorFromHexString_au:[self substringFromIndex:2] alpha:yxAlpha];
        }else {
          color = [UIColor colorFromHexString_au:self alpha:1];
        }
        return color;
    }else {
        return [UIColor clearColor];
    }
}