textfield 限制字数和字符类型

方法1：限制仅为数字
//-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
//  

//    NSCharacterSet *cs;

//    cs = [[NSCharacterSet characterSetWithCharactersInString:@"1234567890"] invertedSet];

//

//    NSString *filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""]; //按cs分离出数组,数组按@""分离出字符串

//    BOOL canChange = [string isEqualToString:filtered];

//  return canChange;

//  

//}

方法2：限制为数字和限制位数。

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{

    // Check for non-numeric characters

    NSUInteger lengthOfString = string.length;

    for (NSInteger loopIndex = 0; loopIndex < lengthOfString; loopIndex++) {//只允许数字输入

        unichar character = [string characterAtIndex:loopIndex];

        if (character < 48) return NO; // 48 unichar for 0

        if (character > 57) return NO; // 57 unichar for 9

    }

    // Check for total length

    NSUInteger proposedNewLength = textField.text.length - range.length + string.length;

    if (proposedNewLength > 11) return NO;//限制长度

    return YES;

}