UIColor转十六进制字符串

方法一：经过测试发现部分颜色会转化为#fffff（五个f），转化残缺导致最后颜色无法还原，不推荐使用。

// UIColor转#ffffff格式的字符串

+ (NSString *)hexFromUIColor:(UIColor *)color

{

    if (CGColorGetNumberOfComponents(color.CGColor) < ) {

        const CGFloat *components = CGColorGetComponents(color.CGColor);

        color = [UIColor colorWithRed:components[]

                                green:components[]

                                 blue:components[]

                                alpha:components[]];

    }

    if (CGColorSpaceGetModel(CGColorGetColorSpace(color.CGColor)) != kCGColorSpaceModelRGB) {

        return [NSString stringWithFormat:@"#FFFFFF"];

    }

    return [NSString stringWithFormat:@"#%x%x%x", (int)((CGColorGetComponents(color.CGColor))[]*255.0),

            (int)((CGColorGetComponents(color.CGColor))[]*255.0),

            (int)((CGColorGetComponents(color.CGColor))[]*255.0)];

}

方法二：完美转化为#ffffff格式，暂未发现问题，推荐使用。

// UIColor转#ffffff格式的字符串

+ (NSString *)hexStringFromColor:(UIColor *)color {

    const CGFloat *components = CGColorGetComponents(color.CGColor);

    CGFloat r = components[];

    CGFloat g = components[];

    CGFloat b = components[];

    return [NSString stringWithFormat:@"#%02lX%02lX%02lX",

            lroundf(r * ),

            lroundf(g * ),

            lroundf(b * )];

}

十六进制字符串转UIColor

方法一：

+ (CGFloat) colorComponentFrom: (NSString *) string start: (NSUInteger) start length: (NSUInteger) length {

    NSString *substring = [string substringWithRange: NSMakeRange(start, length)];

    NSString *fullHex = length ==  ? substring : [NSString stringWithFormat: @"%@%@", substring, substring];

    unsigned hexComponent;

    [[NSScanner scannerWithString: fullHex] scanHexInt: &hexComponent];

    return hexComponent / 255.0;

}

+ (UIColor *) colorWithHexString: (NSString *) hexString {

    NSString *colorString = [[hexString stringByReplacingOccurrencesOfString: @"#" withString: @""] uppercaseString];

    CGFloat alpha, red, blue, green;

    switch ([colorString length]) {

        case : // #RGB

            alpha = 1.0f;

            red   = [self colorComponentFrom: colorString start:  length: ];

            green = [self colorComponentFrom: colorString start:  length: ];

            blue  = [self colorComponentFrom: colorString start:  length: ];

            break;

        case : // #ARGB

            alpha = [self colorComponentFrom: colorString start:  length: ];

            red   = [self colorComponentFrom: colorString start:  length: ];

            green = [self colorComponentFrom: colorString start:  length: ];

            blue  = [self colorComponentFrom: colorString start:  length: ];

            break;

        case : // #RRGGBB

            alpha = 1.0f;

            red   = [self colorComponentFrom: colorString start:  length: ];

            green = [self colorComponentFrom: colorString start:  length: ];

            blue  = [self colorComponentFrom: colorString start:  length: ];

            break;

        case : // #AARRGGBB

            alpha = [self colorComponentFrom: colorString start:  length: ];

            red   = [self colorComponentFrom: colorString start:  length: ];

            green = [self colorComponentFrom: colorString start:  length: ];

            blue  = [self colorComponentFrom: colorString start:  length: ];

            break;

        default:

            return nil;

    }

    return [UIColor colorWithRed: red green: green blue: blue alpha: alpha];

}

方法二：

+ (UIColor *)colorWithHexString:(NSString *)hexString alpha:(CGFloat)alphaValue {

    NSString *cString = [[hexString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];

    if (cString.length < )

    return [UIColor clearColor];

    if ([cString hasPrefix:@"0X"])

    cString = [cString substringFromIndex:];

    if ([cString hasPrefix:@"#"])

    cString = [cString substringFromIndex:];

    if (cString.length != )

    return [UIColor clearColor];

    NSRange range;

    range.location = ;

    range.length = ;

    NSString *rString = [cString substringWithRange:range];

    range.location = ;

    NSString *gString = [cString substringWithRange:range];

    range.location = ;

    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];

    // 注意：myColor是自定义宏

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

    return myColor(r, g, b, alphaValue);

}