- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    UILabel *testLabel=[[UILabel alloc]initWithFrame:CGRectMake(10, 100, 100, 50)];
    testLabel.text=@"1234567890";
    testLabel.backgroundColor=[UIColor orangeColor];
    [self.view addSubview:testLabel];
    
    [self redXingWithLabel:testLabel atIndex:2];
    
   

}
//将字符串特定的1个字变成红色
- (void)redXingWithLabel:(UILabel *)tempLabel atIndex:(NSInteger)tempIndex {
    NSMutableAttributedString * tempString = [[NSMutableAttributedString alloc] initWithString: tempLabel.text];
    [tempString addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:NSMakeRange(tempIndex, 1)];
    tempLabel.attributedText = tempString;
}