iOS UIColor简介

1. UIColor初始化

由白色透明度创建

+ (UIColor *)colorWithWhite:(CGFloat)white alpha:(CGFloat)alpha;

由三原色创建

+ (UIColor *)colorWithRed:(CGFloat)red green:(CGFloat)green blue:(CGFloat)blue alpha:(CGFloat)alpha;

由图片创建

+ (UIColor *)colorWithPatternImage:(UIImage *)image;

设置已有颜色的透明度创建

- (UIColor *)colorWithAlphaComponent:(CGFloat)alpha;

系统颜色

@property(class, nonatomic, readonly) UIColor *blackColor;      // 0.0 white
@property(class, nonatomic, readonly) UIColor *darkGrayColor;   // 0.333 white
@property(class, nonatomic, readonly) UIColor *lightGrayColor;  // 0.667 white
@property(class, nonatomic, readonly) UIColor *whiteColor;      // 1.0 white
@property(class, nonatomic, readonly) UIColor *grayColor;       // 0.5 white
@property(class, nonatomic, readonly) UIColor *redColor;        // 1.0, 0.0, 0.0 RGB
@property(class, nonatomic, readonly) UIColor *greenColor;      // 0.0, 1.0, 0.0 RGB
@property(class, nonatomic, readonly) UIColor *blueColor;       // 0.0, 0.0, 1.0 RGB
@property(class, nonatomic, readonly) UIColor *cyanColor;       // 0.0, 1.0, 1.0 RGB
@property(class, nonatomic, readonly) UIColor *yellowColor;     // 1.0, 1.0, 0.0 RGB
@property(class, nonatomic, readonly) UIColor *magentaColor;    // 1.0, 0.0, 1.0 RGB
@property(class, nonatomic, readonly) UIColor *orangeColor;     // 1.0, 0.5, 0.0 RGB
@property(class, nonatomic, readonly) UIColor *purpleColor;     // 0.5, 0.0, 0.5 RGB
@property(class, nonatomic, readonly) UIColor *brownColor;      // 0.6, 0.4, 0.2 RGB
@property(class, nonatomic, readonly) UIColor *clearColor;      // 0.0 white, 0.0 alpha

2. UIColor自定义颜色

创建一个UIColor的category来自定义颜色。

通过宏自定义颜色

#define ColorWithRGB(R,G,B,A) [UIColor colorWithRed:((R)/255.0) green:((G)/255.0) blue:((B)/255.0) alpha:(A)];

通过十六进制整形自定义颜色

+ (UIColor *)colorWithHex:(NSInteger)hex alpha:(CGFloat)alpha {
    return ColorWithRGB((hex & 0xFF0000) >> 16, (hex & 0xFF00) >> 8, hex & 0xFF, alpha);
}

通过十六进制字符串自定义颜色

+ (UIColor *)colorWithHexString:(NSString *)hexString alpha:(CGFloat)alpha {
    unsigned int red = 0, green = 0, blue = 0;
    [[NSScanner scannerWithString:[hexString substringWithRange:NSMakeRange(0, 2)]] scanHexInt:&red];
    [[NSScanner scannerWithString:[hexString substringWithRange:NSMakeRange(2, 2)]] scanHexInt:&green];
    [[NSScanner scannerWithString:[hexString substringWithRange:NSMakeRange(4, 2)]] scanHexInt:&blue];

    return ColorWithRGB(red, green, blue, alpha);
}

3. 生成UIImage

创建一个UIColor的category类

- (UIImage *)covertToImage {
    CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
    UIGraphicsBeginImageContext(rect.size);

    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [self CGColor]);
    CGContextFillRect(context, rect);

    UIImage *colorImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return colorImage;
}

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