iOS 十六进制字符串 "#FFFF00" 转换成颜色对象 

 1 + (UIColor *)colorWithHexStr:(NSString *)hexString {
 2     NSString *colorString = [[hexString stringByReplacingOccurrencesOfString:@"#" withString:@""] uppercaseString];
 3     CGFloat alpha, red, blue, green;
 4     switch ([colorString length]) {
 5         case 3: // #RGB
 6             alpha = 1.0f;
 7             red   = [self colorComponentFrom: colorString start: 0 length: 1];
 8             green = [self colorComponentFrom: colorString start: 1 length: 1];
 9             blue  = [self colorComponentFrom: colorString start: 2 length: 1];
10             break;
11         case 4: // #ARGB
12             alpha = [self colorComponentFrom: colorString start: 0 length: 1];
13             red   = [self colorComponentFrom: colorString start: 1 length: 1];
14             green = [self colorComponentFrom: colorString start: 2 length: 1];
15             blue  = [self colorComponentFrom: colorString start: 3 length: 1];
16             break;
17         case 6: // #RRGGBB
18             alpha = 1.0f;
19             red   = [self colorComponentFrom: colorString start: 0 length: 2];
20             green = [self colorComponentFrom: colorString start: 2 length: 2];
21             blue  = [self colorComponentFrom: colorString start: 4 length: 2];
22             break;
23         case 8: // #AARRGGBB
24             alpha = [self colorComponentFrom: colorString start: 0 length: 2];
25             red   = [self colorComponentFrom: colorString start: 2 length: 2];
26             green = [self colorComponentFrom: colorString start: 4 length: 2];
27             blue  = [self colorComponentFrom: colorString start: 6 length: 2];
28             break;
29         default:
30             return nil;
31             break;
32     }
33     return [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
34 }
35 
36 + (CGFloat)colorComponentFrom:(NSString *)string start:(NSUInteger)start length:(NSUInteger)length {
37     NSString *substring = [string substringWithRange: NSMakeRange(start, length)];
38     NSString *fullHex = length == 2 ? substring : [NSString stringWithFormat: @"%@%@", substring, substring];
39     unsigned hexComponent;
40     [[NSScanner scannerWithString: fullHex] scanHexInt: &hexComponent];
41     return hexComponent / 255.0;
42 }

 

posted on 2018-11-15 16:57  活最好的自己  阅读(2182)  评论(0)    收藏  举报

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