iOS label显示不同颜色的字体

在项目中我们会遇到很多在label上显示不同颜色字体的情况，网上有很多的第三方类库像什么AttributedLabel、TTTAttributedLabel之类的，今天我在这只是记录下他的简单实现，

NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:@"Using NSAttributed String，try your best to test attributed string text"];  
 [str addAttribute:NSForegroundColorAttributeName value:[UIColor blueColor] range:NSMakeRange(0,5)];  
 [str addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:NSMakeRange(6,12)];  
 [str addAttribute:NSForegroundColorAttributeName value:[UIColor greenColor] range:NSMakeRange(19,6)];  
 [str addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"Arial" size:30.0] range:NSMakeRange(0, 5)];  
 [str addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"Arial" size:30.0] range:NSMakeRange(6, 12)];  
 [str addAttribute:NSFontAttributeName value:[UIFont fontWithName:@"Arial" size:30.0] range:NSMakeRange(19, 6)];  
   
 UILabel *attrLabel = [[UILabel alloc] initWithFrame:CGRectMake(20, 150, 320 - 40, 90)];  
 attrLabel.attributedText = str;  
 attrLabel.numberOfLines = 0;  
 [self.view addSubview:attrLabel];