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  • 使用十六进制色值表示UIColor

    假如你有一个值为 @”0A5CEA” (字符串类型的16进制色值) ,可以如下方法创建UIColor对象:

    UIColor *color = [UIColor colorwithHexString:@"0A5CEA" alpha:.9];

    UIColor Category

    然后我们来创建一个UIColor Category,

    声明代码 UIColor+fromHex.h :

    @interface UIColor (fromHex)
    + (UIColor *)colorwithHexString:(NSString *)hexStr alpha:(CGFloat)alpha;
    @end

    implementation代码 UIColor+fromHex.m :

     1 @implementation UIColor (fromHex)
     2  
     3 + (UIColor *)colorwithHexString:(NSString *)hexStr alpha:(CGFloat)alpha;
     4 {
     5   //-----------------------------------------
     6   // Convert hex string to an integer
     7   //-----------------------------------------
     8   unsigned int hexint = 0;
     9  
    10   // Create scanner
    11   NSScanner *scanner = [NSScanner scannerWithString:hexStr];
    12  
    13   // Tell scanner to skip the # character
    14   [scanner setCharactersToBeSkipped:[NSCharacterSet 
    15     characterSetWithCharactersInString:@"#"]];
    16   [scanner scanHexInt:&hexint];
    17  
    18   //-----------------------------------------
    19   // Create color object, specifying alpha
    20   //-----------------------------------------
    21   UIColor *color =
    22     [UIColor colorWithRed:((CGFloat) ((hexint & 0xFF0000) >> 16))/255
    23     green:((CGFloat) ((hexint & 0xFF00) >> 8))/255
    24     blue:((CGFloat) (hexint & 0xFF))/255
    25     alpha:alpha];
    26  
    27   return color;
    28 }
    29  
    30 @end

    第8-15行 对 hex value 转换为 unsigned integer.

    第20-24行 创建一个 UIColor object 通过位操作 ‘&’ 计算各RGB颜色值, 同时除以255得到float值。

    下面示例代码, 包括十六进制值格式“0x0A5CEA” 和@”#0A5CEA” (后者一般用于web开发):

     1 NSString *hexStr1 = @"123ABC";
     2 NSString *hexStr2 = @"#123ABC";
     3 NSString *hexStr3 = @"0x123ABC";
     4  
     5 UIColor *color1 = [UIColor colorwithHexString:hexStr1 alpha:.9];
     6 NSLog(@"UIColor: %@", color1);
     7  
     8 UIColor *color2 = [UIColor colorwithHexString:hexStr2 alpha:.9];
     9 NSLog(@"UIColor: %@", color2);
    10  
    11 UIColor *color3 = [UIColor colorwithHexString:hexStr3 alpha:.9];
    12 NSLog(@"UIColor: %@", color3);

    结果如下:

    UIColor: UIDeviceRGBColorSpace 0.0705882 0.227451 0.737255 0.9
    UIColor: UIDeviceRGBColorSpace 0.0705882 0.227451 0.737255 0.9
    UIColor: UIDeviceRGBColorSpace 0.0705882 0.227451 0.737255 0.9
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  • 原文地址:https://www.cnblogs.com/samniu/p/3804397.html
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