隨手寫了個，支持選擇刪除 可自己優化封裝使用，有問題請評論

- (IBAction)textChange:(UITextField *)textField {

    //去空
    NSString * string = [textField.text stringByReplacingOccurrencesOfString:@" " withString:@""];
    if (!string.length) {
        textField.text = @"";
        return;
    }
    if (string.length >= 11) {
        string = [string substringToIndex:11];
    }
    NSNumber * number = [NSNumber numberWithInteger:[string integerValue]];
    NSNumberFormatter * formatter = [NSNumberFormatter new];
    //設置分隔符
    [formatter setGroupingSeparator:@" "];
    //設置使用組分割
    formatter.usesGroupingSeparator = YES;
    // 數字分割的尺寸<從右向左>
    formatter.groupingSize = ([string length]-3)%4>0?([string length]-3)%4:4;
    //除了groupingSize決定的尺寸外,其他數字位分割的尺寸
    formatter.secondaryGroupingSize = [string length]>7?4:3;
    //獲取格式化后765的字符
    textField.text  = [formatter stringFromNumber:number];
    if (position) {
        textField.selectedTextRange = selrange;
    }
    
    
}

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    
    selrange = textField.selectedTextRange;
    NSInteger location = [textField offsetFromPosition:textField.beginningOfDocument toPosition:selrange.end];
    NSLog(@"location =%zi",location);
    NSInteger index;
    if ([string isEqualToString:@""]) {
        index = location%5?-1:-2;
    } else {
        index = (location-3)%5?1:2;
    }
    position = [textField positionFromPosition:selrange.start offset:index];
    selrange = [textField textRangeFromPosition:position toPosition:position];
    NSLog(@"%@,%@",position,selrange);
    if (textField.text.length >= 13 && ![string isEqualToString:@""]) {
        return NO;
    }
    return YES;
    
}