UIColor

• UIColor、CIColor 和 CGColor 出如今不一樣的類庫裏面，其實就是顏色存儲方式不一樣而已，好比 999 能夠用 10 進制、2 進制、16 進制等存儲。三者之間都是可以方便轉換的，特別是不少構造函數。

0、極速宏

/** 顏色生成 */
#define CHColor_A(r,g,b,a) [UIColor colorWithRed:r/255.f green:g/255.f blue:b/255.f alpha:a]
/** 顏色生成 */
#define CHColor(r,g,b) CHColor_A(r,g,b,1.0)

/** 十六進制顏色 -> 0x123456 */
#define CHRGB16HEX(hex_0x) [UIColor colorWithRed:((float)((hex_0x & 0xFF0000) >> 16))/255.0 green:((float)((hex_0x & 0xFF00) >> 8))/255.0 blue:((float)(hex_0x & 0xFF))/255.0 alpha:1.0]

#define CHRGB16HEX_A(hex_0x, a) [UIColor colorWithRed:((float)((hex_0x & 0xFF0000) >> 16))/255.0 green:((float)((hex_0x & 0xFF00) >> 8))/255.0 blue:((float)(hex_0x & 0xFF))/255.0 alpha:a]

/** 設置隨機顏色 */
#define CHRandomColor     [UIColor colorWithRed:arc4random_uniform(256)/255.0 green:arc4random_uniform(256)/255.0 blue:arc4random_uniform(256)/255.0 alpha:1.0]

/** 黑色 */
#define Black_Color       [UIColor blackColor]
/** 深灰色 */
#define DarkGray_Color    [UIColor darkGrayColor]
/** 淺灰色 */
#define LightGray_Color   [UIColor lightGrayColor]
/** 白色 */
#define White_Color       [UIColor whiteColor]
/** 灰色 */
#define Gray_Color        [UIColor grayColor]
/** 紅色 */
#define Red_Color         [UIColor redColor]
/** 綠色 */
#define Green_Color       [UIColor greenColor]
/** 藍色 */
#define Blue_Color        [UIColor blueColor]
/** 藍綠色 */
#define Cyan_Color        [UIColor cyanColor]
/** 黃色 */
#define Yellow_Color      [UIColor yellowColor]
/** 品紅色 */
#define Magenta_Color     [UIColor magentaColor]
/** 橘黃色 */
#define Orange_Color      [UIColor orangeColor]
/** 紫色 */
#define Purple_Color      [UIColor purpleColor]
/** 棕色 */
#define Brown_Color       [UIColor brownColor]
/** 透明色 */
#define Clear_Color       [UIColor clearColor]

一、UIColor 的建立

• 1.1 使用系統定義好的顏色建立

UIColor *color1 = [UIColor blueColor];
// 附帶設置顏色的透明度
UIColor *color1 = [[UIColor blackColor] colorWithAlphaComponent:0.5];

• 1.2 由白色透明度建立

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

• 1.3 由三原色建立

// arc4random()%256/255.0 獲取小於等於 1 大於 0 的隨機數字
CGFloat red = arc4random()%256/255.0;
CGFloat green = arc4random()%256/255.0;
CGFloat blue = arc4random()%256/255.0;

// Red，green，blue 值的範圍是 0 ～ 1，alpha：透明度，1 不透明
UIColor *color3 = [UIColor colorWithRed:red green:green blue:blue alpha:1];

• 1.4 由圖片建立

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

• 1.5 由 16 進制字符串建立

NSString *colorString = @"#FF0000";

// 十六進制數字字符串轉十進制數字
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 值的範圍是 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];

二、UIColor 與 CIColor 和 CGColor 的相互轉換

// UIColor 轉 CGColor
CGColorRef color = [[UIColor greenColor] CGColor];

// CGColor 轉 UIColor
UIColor *CG_To_UIColor = [UIColor colorWithCGColor:self.outerCircleV.layer.borderColor];

三、由十六進制顏色值建立 RGB 顏色值

• 適用於 0Xc83c2三、#c83c2三、c83c23 格式的十六進制顏色值。

/// 由十六進制顏色值建立 RGB 顏色值，帶透明度設置
+ (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];
}

/// 由十六進制顏色值建立 RGB 顏色值
+ (UIColor *)colorWithHexString:(NSString *)color {

	return [UIColor colorWithHexString:color alpha:1.0f];
}

// 0X 前綴格式
UIColor *color = [UIColor colorWithHexString:@"0Xc83c23"];
UIColor *color = [UIColor colorWithHexString:@"0Xc83c23" alpha:0.5];

// # 前綴格式
UIColor *color = [UIColor colorWithHexString:@"#c83c23"];
UIColor *color = [UIColor colorWithHexString:@"#c83c23" alpha:0.5];

// 無前綴格式
UIColor *color = [UIColor colorWithHexString:@"c83c23"];
UIColor *color = [UIColor colorWithHexString:@"c83c23" alpha:0.5];

四、其餘

• 4.1 iOS 判斷兩個顏色是否相同