UITextView占位符

self.textView.delegate = self;
//开始编辑

• (void)textViewDidBeginEditing:(UITextView *)textView {
  if ([self.textView.text isEqualToString:@""]) {
  textView.text = @"";
  self.textView.textColor = [UIColor blackColor];
  }
  }
  //在结束编辑的代理方法中进行如下操作
• (void)textViewDidEndEditing:(UITextView *)textView {
  if (textView.text.length<1) {
  self.textView.text = @"";
  self.textView.textColor = colorText;
  }
  }