UITextView 增加水印提醒

#pragma mark ------- 增加textView水印提示语
 - (void) setPlaceholder{

self.infoTextView.textColor = [UIColor lightGrayColor];
self.infoTextView.text = NSLocalizedString(@"输入您的需求或资源", nil);
self.infoTextView.selectedRange = NSMakeRange(0, 0);
self.infoTextView.font = [UIFont systemFontOfSize:13];
//我代理写在 xib里了  然后还要UITextViewDelegate 
}    

- (void)textViewDidChangeSelection:(UITextView *)textView 
{
if (textView.textColor==[UIColor lightGrayColor])//如果是提示内容，光标放置开始位置
{
    NSRange range;
    range.location = 0;
    range.length = 0;
    textView.selectedRange = range;
}
}
-(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString*)text
{
if (![text isEqualToString:@""]&&textView.textColor==[UIColor lightGrayColor])//如果不是delete响应,当前是提示信息，修改其属性
{
    textView.text=@"";//置空
    textView.textColor=[UIColor blackColor];
}

if ([text isEqualToString:@"\n"])//回车事件
{
    if ([textView.text isEqualToString:@""])//如果直接回车，显示提示内容
    {
        textView.textColor=[UIColor lightGrayColor];
        textView.text=NSLocalizedString(@"输入您的需求或资源", nil);
    }
//        [textView resignFirstResponder];//隐藏键盘
    return NO;
}
return YES;
}
- (void)textViewDidChange:(UITextView *)textView
{
if ([textView.text isEqualToString:@""])
{
    textView.textColor=[UIColor lightGrayColor];
    textView.text=NSLocalizedString(@"输入您的需求或资源", nil);
}
}