iOS关于UITextView自定义PlaceHolder

• 开发过程中有收获会使用到输入框，但是UITextField又不可以换行，使用UITextView虽然可以换行，但是却没有PlaceHolder，下面介绍如何使用，UITextView中添加一个label默认位是PlaceHolder
  #import "ViewController.h"
  @interface ViewController ()
  @property(nonatomic,strong)UILabel *label;
  @end
• 在viewDidload方法中创建textview和label
  UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(50, 100, 300, 100)];
  textView.delegate = self;
  textView.layer.borderColor =[UIColor redColor].CGColor;
  textView.layer.borderWidth = 1.0;
  _label = [[UILabel alloc] initWithFrame:CGRectMake(55, 102, 100, 20)];
  _label.text = @"请输入东西";
  [self.view addSubview:textView];
  [self.view addSubview:self.label];
• 然后再UITextView的delegate里边做相应地逻辑处理
  - (BOOL)textViewShouldBeginEditing:(UITextView *)textView{
  if ([textView.text isEqualToString:@""]) {
  _label.text = @" ";
  }else{
  _label.text = @"";
  }
  return YES;
  }
  -(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
  {
  if ([text isEqualToString:@"\n"]) {
  if ([textView.text isEqualToString:@""] ||textView.text== nil) {
  _label.text = @"请输入东西";
  }
  [textView resignFirstResponder];
  return NO;
  }
  return YES;
  }