完美解决UITextField中文输入长度限制问题.

 因为中文输入有选择的问题 所以

经过测试之后 下面的代码完美 解决 这是oc的代码 swfit同理.

@property (assign, nonatomic) NSInteger checkLength;

// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
    // Drawing code
    [super drawRect:rect];
    self.delegate                = self;
    self.checkLength = 16;//默认长度限制
    [self setKeyboardType:UIKeyboardTypeDefault];
    [self addTarget:self action:@selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];
}
- (void)textFieldDidChange:(UITextField *)textField{
    NSMutableString *text = [textField.text mutableCopy];
    NSString * string = [text stringByReplacingOccurrencesOfString:@" " withString:@""];
    NSLog(@"%@", string);
    if (string.length > self.checkLength) {
        textField.text = [textField.text substringToIndex:self.checkLength];
    }
}

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    if (string.length == 0) {
        //<- 删除
        return true;
    }
    NSMutableString *text = [textField.text mutableCopy];
    NSString * string1 = [text stringByReplacingOccurrencesOfString:@" " withString:@""];
    if (string1.length < self.checkLength) {
        return true;
    }else{
        return false;
    }
}