1、UIColor 的创建

1.1 使用系统定义好的颜色创建

UIColor *color1 = [UIColor blueColor];// 附带设置颜色的透明度UIColor *color1 = [[UIColor blackColor] colorWithAlphaComponent:0.5];

1.2 由白色透明度创建

// alpha：透明度，1 不透明UIColor *color2 = [UIColor colorWithWhite:1 alpha:0.5];

1.3 由三原色创建

// arc4random()%256/255.0 获取小于等于 1 大于 0 的随机数字CGFloat red = arc4random()%256/255.0;CGFloat green = arc4random()%256/255.0;CGFloat blue = arc4random()%256/255.0;// Red，green，blue 值的范围是 0 ～ 1，alpha：透明度，1 不透明UIColor *color3 = [UIColor colorWithRed:red green:green blue:blue alpha:1];

1.4 由图片创建

UIColor *color4 = [UIColor colorWithPatternImage:[UIImage imageNamed:@"13"]];

1.5 由 16 进制字符串创建

NSString *colorString = @"#FF0000";// 十六进制数字字符串转十进制数字NSString *s1 = [colorString substringWithRange:NSMakeRange(1, 2)];unsigned long c1 = strtoul([s1 UTF8String], 0, 16);NSString *s2 = [colorString substringWithRange:NSMakeRange(3, 2)];unsigned long c2 = strtoul([s2 UTF8String], 0, 16);NSString *s3 = [colorString substringWithRange:NSMakeRange(5, 2)];unsigned long c3 = strtoul([s3 UTF8String], 0, 16);// Red，green，blue 值的范围是 0 ～ 1，alpha：透明度，1 不透明UIColor *color5 = [UIColor colorWithRed:c1/255.0 green:c2/255.0 blue:c3/255.0 alpha:1];

2、UIColor 与 CIColor 和 CGColor 的相互转换

// UIColor 转 CGColorCGColorRef color = [[UIColor greenColor] CGColor];// CGColor 转 UIColorUIColor *CG_To_UIColor = [UIColor colorWithCGColor:self.outerCircleV.layer.borderColor];

3、由十六进制颜色值创建 RGB 颜色值

适用于 0Xc83c23、#c83c23、c83c23 格式的十六进制颜色值。

/// 由十六进制颜色值创建 RGB 颜色值，带透明度设置+ (UIColor *)colorWithHexString:(NSString *)color alpha:(CGFloat)alpha {    NSString *cString = [[color stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];    // String should be 6 or 8 characters    if ([cString length] < 6) {        return [UIColor clearColor];    }    // strip "0X" or "#" if it appears    if ([cString hasPrefix:@"0X"])        cString = [cString substringFromIndex:2];    if ([cString hasPrefix:@"#"])        cString = [cString substringFromIndex:1];    if ([cString length] != 6)        return [UIColor clearColor];    // Separate into r, g, b substrings    NSRange range;    range.location = 0;    range.length = 2;    // r、g、b    NSString *rString = [cString substringWithRange:range];    range.location = 2;    NSString *gString = [cString substringWithRange:range];    range.location = 4;    NSString *bString = [cString substringWithRange:range];    // Scan values    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:alpha];}/// 由十六进制颜色值创建 RGB 颜色值+ (UIColor *)colorWithHexString:(NSString *)color {    return [UIColor colorWithHexString:color alpha:1.0f];}// 0X 前缀格式UIColor *color = [UIColor colorWithHexString:@"0Xc83c23"];UIColor *color = [UIColor colorWithHexString:@"0Xc83c23" alpha:0.5];// # 前缀格式UIColor *color = [UIColor colorWithHexString:@"#c83c23"];UIColor *color = [UIColor colorWithHexString:@"#c83c23" alpha:0.5];// 无前缀格式UIColor *color = [UIColor colorWithHexString:@"c83c23"];UIColor *color = [UIColor colorWithHexString:@"c83c23" alpha:0.5];