iOS-textField(银行卡号输入格式)

最近写的项目有这个需求,看了别人写的,打算自己写一份备用

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

• 第一步需要有一个textField,遵守协议,实现代理
  self.mytextfield.delegate = self;
  -然后需要实现的代理方法就是这个
  - (BOOL)textField:(UITextField )textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString )string{
  //判断是否是当前输入框
  if (self.mytextfield == textField) {
  NSString text = self.mytextfield.text;
  //限制字符 至于那个\b用在search中 写不写都行
  NSCharacterSet characterSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789\b"];
  //去掉空格
  string = [string stringByReplacingOccurrencesOfString:@" " withString:@""];
  //检查除数字之外的字符 invertedSet:意思是取反,除了数字和退格的内容
  if ([string rangeOfCharacterFromSet:[characterSet invertedSet]].location != NSNotFound) {
  return NO;
  }
  //拼接text 要输入的部分+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)];
  }
  //去掉除数字部分
  newString = [newString stringByTrimmingCharactersInSet:[characterSet invertedSet]];
  // 限制长度
  if (newString.length >= 24) {
  return NO;
  }
  //赋值
  [self.mytextfield setText:newString];
  return NO;
  }
  return YES;
  }

基本就是这样,注释写的很详细了