iOS UITextField輸入框實現(xiàn)輸入手機號時自動添加空格

前景：需求很簡單，輸入框手機號自動加空格，度娘方法一大堆，但是都有bug啊，要么空格不能刪除，要么光標輸入錯位，總之，一言難盡，公司之前的一個小伙伴寫了一堆邏輯，但是也不能解決所有的問題，不完美，測試測出來被告知，“要加空格就是這樣，我解決不了”，當時我也沒在意。以為影響不到，直到最近，這個問題被無限放大了，問題是：把光標移動到中間輸入一個后，光標就會跳到最后的位置，這樣導致用戶輸入的手機號就不對，然后就去改，改了又改，永遠輸不對，這玩?zhèn)€屁，直接卸載了...
好了，不啰嗦了，直接上代碼！

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
   NSString *text = [textField text];
   NSInteger init = text.length; // 初始
   NSCharacterSet *characterSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789\b"];
   string = [string stringByReplacingOccurrencesOfString:@" " withString:@""];
   if ([string rangeOfCharacterFromSet:[characterSet invertedSet]].location != NSNotFound) {
       return NO;
   }
   text = [text stringByReplacingCharactersInRange:range withString:string];
   text = [text stringByReplacingOccurrencesOfString:@" " withString:@""];
   // 如果是電話號碼格式化，需要添加這三行代碼
   NSMutableString *temString = [NSMutableString stringWithString:text];
   [temString insertString:@" " atIndex:0];
   text = temString;
   NSString *newString = @"";
   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)];
   }

   newString = [newString stringByTrimmingCharactersInSet:[characterSet invertedSet]];
   NSInteger num = newString.length-init; // 增加的位數(shù)
   if (num < 0) {
       num = 1;
   }
   if (newString.length >= 14) {
       return NO;
   }
   [textField setText:newString];
   self.loginButton.enabled = newString.length == 13; // 按鈕的點擊狀態(tài)
   // 刪除操作
   if (range.length == 1 && string.length == 0) {
       [self cursorLocation:textField index:range.location];
   }else {
       [self cursorLocation:textField index:range.location+num];
   }
   return NO;
}

// 改變光標位置
- (void)cursorLocation:(UITextField*)textField index:(NSInteger)index {
   NSInteger length = textField.text.length;
   if (length<index) {
       index = length;
   }
   NSRange range = NSMakeRange(index, 0);
   UITextPosition *start = [textField positionFromPosition:[textField beginningOfDocument] offset:range.location];
   UITextPosition *end = [textField positionFromPosition:start offset:range.length];
   [textField setSelectedTextRange:[textField textRangeFromPosition:start toPosition:end]];
}