iOSUILabel实现部分字段更改样式使用

利用iOS7的label特性对abel进行封装使用

对一段字符串当中的某段进行颜色变化,直接掉用加方法就可以显示

```

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
   
    UILabel *labelDemo = [[UILabel alloc] initWithFrame:CGRectMake(10, 50, 300, 40)];
    [self.view addSubview:labelDemo];
    NSString *originalString = @"今天是：星期日";
    NSString *changeString = @"星期日";
    labelDemo.attributedText = [ViewController changeLabelColorOriginalString:originalString changeString:changeString];
}

+ (NSMutableAttributedString *)changeLabelColorOriginalString:(NSString *)originalString changeString:(NSString *)changeString {
    NSRange changeStringRange = [originalString rangeOfString:changeString];
    NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:originalString];
    [attributedString addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:changeStringRange];
    return attributedString;
}

```

}