UIColor类的扩展

- (UIColor *) colorWithHexString: (NSString *) stringToConvert
{
    NSString *cString = [[stringToConvert stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];
   

    if ([cString length] < 6) 
        return [UIColor whiteColor];
    if ([cString hasPrefix:@"#"]) 
        cString = [cString substringFromIndex:1];
    if ([cString length] != 6) 
        return [UIColor whiteColor];
         
    NSRange range;
    range.location = 0;
    range.length = 2;
    NSString *rString = [cString substringWithRange:range];
   
    range.location = 2;
    NSString *gString = [cString substringWithRange:range];
    
    range.location = 4;
    NSString *bString = [cString substringWithRange:range];
    

    unsigned int r, g, b;
    [[NSScanner scannerWithString:rString] scanHexInt:&r];
    [[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];
}

2.  一个颜色转换成16进制

//颜色转字符串
- (NSString *) changeUIColorToRGB:(UIColor *)color{
    
    
    const CGFloat *cs=CGColorGetComponents(color.CGColor);
    
    
    NSString *r = [NSString stringWithFormat:@"%@",[self  ToHex:cs[0]*255]];
    NSString *g = [NSString stringWithFormat:@"%@",[self  ToHex:cs[1]*255]];
    NSString *b = [NSString stringWithFormat:@"%@",[self  ToHex:cs[2]*255]];
    return [NSString stringWithFormat:@"#%@%@%@",r,g,b];


}


//十进制转十六进制
-(NSString *)ToHex:(int)tmpid
{
    NSString *endtmp=@"";
    NSString *nLetterValue;
    NSString *nStrat;
    int ttmpig=tmpid%16;
    int tmp=tmpid/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];
            
    }
    switch (tmp)
    {
        case 10:
            nStrat =@"A";break;
        case 11:
            nStrat =@"B";break;
        case 12:
            nStrat =@"C";break;
        case 13:
            nStrat =@"D";break;
        case 14:
            nStrat =@"E";break;
        case 15:
            nStrat =@"F";break;
        default:nStrat=[[NSString alloc]initWithFormat:@"%i",tmp];
            
    }
    endtmp=[[NSString alloc]initWithFormat:@"%@%@",nStrat,nLetterValue];
    return endtmp;
}