最近寫的項目有這個需求,看了別人寫的,打算自己寫一份備用

這是原文[http://blog.csdn.net/h3c4lenovo/article/details/8515304]

• 第一步需要有一個textField,遵守協(xié)議,實現(xiàn)代理
  self.mytextfield.delegate = self;
  -然后需要實現(xiàn)的代理方法就是這個
  - (BOOL)textField:(UITextField )textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString )string{
  //判斷是否是當前輸入框
  if (self.mytextfield == textField) {
  NSString text = self.mytextfield.text;
  //限制字符 至于那個\b用在search中 寫不寫都行
  NSCharacterSet characterSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789\b"];
  //去掉空格
  string = [string stringByReplacingOccurrencesOfString:@" " withString:@""];
  //檢查除數(shù)字之外的字符 invertedSet:意思是取反,除了數(shù)字和退格的內(nèi)容
  if ([string rangeOfCharacterFromSet:[characterSet invertedSet]].location != NSNotFound) {
  return NO;
  }
  //拼接text 要輸入的部分+原有的
  text = [text stringByReplacingCharactersInRange:range withString:string];
  //去空格
  text = [text stringByReplacingOccurrencesOfString:@" " withString:@""];
  NSString newString = @"";
  //四位添加空格
  while (text.length > 0) {
  NSString subString = [text substringToIndex:MIN(text.length, 4)];
  newString = [newString stringByAppendingString:subString];
  if (subString.length == 4) {
  newString = [newString stringByAppendingString:@" "];
  }
  text = [text substringFromIndex:MIN(text.length, 4)];
  }
  //去掉除數(shù)字部分
  newString = [newString stringByTrimmingCharactersInSet:[characterSet invertedSet]];
  // 限制長度
  if (newString.length >= 24) {
  return NO;
  }
  //賦值
  [self.mytextfield setText:newString];
  return NO;
  }
  return YES;
  }

基本就是這樣,注釋寫的很詳細了