UITextField最大字符数和最大字节数的限制
2334471588
7年前
<p>UITextView , UITextfield 中有很多坑，网上的方法也很多。但是并不是很全面吧，这里全面进行了总结，并进行了封装。欢迎大家下载。</p> <h3><strong>一. 字符限制</strong></h3> <p><strong>1. 错误方法</strong></p> <p>常见的这种方法是错误的，会导致Emoj表情的截取问题</p> <pre> <code class="language-objectivec">- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string { if(range.length + range.location > textField.text.length) { return NO; } NSUInteger newLength = [textField.text length] + [string length] - range.length; return newLength <= 5; } </code></pre> <p>这种限制方法会导致拼音下出现这种情况，且无法输入.无法输入满5个字符。在emoj表情也有问题</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/e9246319ca4939fed488269d817ed79f.jpg"></p> <p style="text-align:center"><img src="https://simg.open-open.com/show/6efc4b881d298ea92c9b7a48e398bb31.jpg"></p> <p style="text-align:center"><img src="https://simg.open-open.com/show/00ea5cc58b00e67764f80b343cded1d0.jpg"></p> <p><strong>2. 推荐方法</strong></p> <p>使用rangeOfComposedCharacterSequencesForRange, 防止在range范围内整词被截断</p> <pre> <code class="language-objectivec">- (void)textFieldDidChange:(UITextField *)textField { NSString *toBeString = textField.text; UITextRange *selectedRange = [textField markedTextRange]; UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0]; // 没有高亮选择的字，则对已输入的文字进行字数统计和限制,防止中文被截断 if (!position){ if (toBeString.length > _maxLength){ //中文和emoj表情存在问题，需要对此进行处理 NSRange rangeRange = [toBeString rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, _maxLength)]; textField.text = [toBeString substringWithRange:rangeRange]; } } } </code></pre> <p style="text-align:center"><img src="https://simg.open-open.com/show/bd83777889157c3fbf64e07ef2fdf673.jpg"></p> <h3><strong>二. 字节限制</strong></h3> <p><strong>1. 限制字节数</strong></p> <p>在UTF8中，英文和数字是1个字节,汉子是3个字节，emoji是3或者4个字节。这里的难度比上面更大，如果截取失败，极有可能出现乱码。这里我们的做法如下</p> <pre> <code class="language-objectivec">- (void)textFieldDidChange:(UITextField *)textField { NSString *toBeString = textField.text; //---字节处理 NSInteger bytesCount = strlen([textField.text UTF8String]); if (bytesCount > _maxBytesLength) { NSString *content = [textField.text subStrWithUtf8Len:(int)_maxBytesLength]; textField.text = content; } } - (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{ NSString * inputString = [textField.text stringByReplacingCharactersInRange:range withString:string]; //限制字节数 if ([inputString length] > 0){ NSInteger len = strlen([inputString UTF8String]); if (len > _maxBytesLength){ return NO; } else { return YES; } } return YES; } </code></pre> <p>这里不能只在进行限制，在textFieldDidChange中需要对中文联想做处理才行</p> <h3><strong>三. 放弃键盘</strong></h3> <p><strong>1. 能拿到uitextfield的时候用</strong></p> <pre> <code class="language-objectivec">- (BOOL)textFieldShouldReturn:(UITextField *)textField { return [textField resignFirstResponder]; } </code></pre> <p>2. 点击view消失的时候用</p> <pre> <code class="language-objectivec">[self.view endEditing:YES]; </code></pre> <p>3. 难以获取的时候用</p> <pre> <code class="language-objectivec">[[UIApplication sharedApplication] sendAction:@selector(resignFirstResponder) to:nil from:nil forEvent:nil]; </code></pre> <p>或者</p> <pre> <code class="language-objectivec">[[[UIApplication sharedApplication] keyWindow] endEditing:YES]; </code></pre> <p><strong>2.Tableview点击空白处或者滚动时消失</strong></p> <pre> <code class="language-objectivec">{ UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(fingerTapped:)]; [self.view addGestureRecognizer:singleTap]; } #pragma mark- 键盘消失 -(void)fingerTapped:(UITapGestureRecognizer *)gestureRecognizer{ [self.view endEditing:YES]; } -(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{ [self.view endEditing:YES]; } </code></pre> <h3><strong>四. 正则表达式限制</strong></h3> <p>请参考 正则表达式语法表 ,这里我提供了两种表达式给大家参考，一个Int,一个无unsignedInt</p> <pre> <code class="language-objectivec">-(BOOL) isTextFieldMatchWithRegularExpression:(NSString *)exporession{ NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",exporession]; return [predicate evaluateWithObject:self]; } -(BOOL) isTextFieldIntValue{ return [self isTextFieldMatchWithRegularExpression:@"[-]{0,1}[0-9]*"]; } -(BOOL) isTextFieldUnsignedIntValue{ return [self isTextFieldMatchWithRegularExpression:@"[0-9]+"]; } </code></pre> <h3><strong>五. UITextfield的键盘事件多次回调问题</strong></h3> <p><strong>1.键盘高度遮挡问题</strong></p> <p>一般出现遮挡的时候我们用以下代码,看看当前textfield是否在键盘下面，在的话算出键盘的顶端和textfield的底部的距离，然后做偏移动画</p> <pre> <code class="language-objectivec">- (void)keyboardWillShow:(NSNotification *)notification { NSDictionary *userInfo = [notification userInfo]; NSValue* aValue = [userInfo objectForKey:UIKeyboardFrameEndUserInfoKey]; CGRect keyboardRect = [aValue CGRectValue]; keyboardRect = [self.view convertRect:keyboardRect fromView:nil]; CGFloat keyboardTop = keyboardRect.origin.y; CGFloat offset = self.normalTextField.frame.size.height + self.normalTextField.frame.origin.y - keyboardTop; NSValue *animationDurationValue = [userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey]; NSTimeInterval animationDuration; [animationDurationValue getValue:&animationDuration]; if(offset > 0){ // Animate the resize of the text view's frame in sync with the keyboard's appearance. [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:animationDuration]; CGRect rect = CGRectMake(0.0f, -offset,self.view.frame.size.width,self.view.frame.size.height); self.view.frame = rect; [UIView commitAnimations]; } } </code></pre> <ol> <li> <p>真机</p> <p>如果使用了中文输入法，注册的keyboardWillShow会回调两次。第一次是键盘默认高度216，第二次则是加了keyboard的导航栏的高度。</p> </li> <li> <p>模拟器</p> <p>第一次弹出键盘没有问题</p> </li> </ol> <p style="text-align:center"><img src="https://simg.open-open.com/show/e0923a0f2fa276e1eaac2c4b21667f4b.png"></p> <p>打印userinfo:</p> <pre> <code class="language-objectivec">(lldb) po userInfo { UIKeyboardAnimationCurveUserInfoKey = 7; UIKeyboardAnimationDurationUserInfoKey = "0.25"; UIKeyboardBoundsUserInfoKey = "NSRect: {{0, 0}, {414, 226}}"; UIKeyboardCenterBeginUserInfoKey = "NSPoint: {207, 849}"; UIKeyboardCenterEndUserInfoKey = "NSPoint: {207, 623}"; UIKeyboardFrameBeginUserInfoKey = "NSRect: {{0, 736}, {414, 226}}"; UIKeyboardFrameEndUserInfoKey = "NSRect: {{0, 510}, {414, 226}}"; UIKeyboardIsLocalUserInfoKey = 1; } </code></pre> <p>此时我们去按123旁边的小圆球会出现如下的图：</p> <p style="text-align:center"><img src="https://simg.open-open.com/show/08006c07364dded2bcba7db8d2966b8f.png"></p> <p>打印userinfo:</p> <pre> <code class="language-objectivec">(lldb) po userInfo { UIKeyboardAnimationCurveUserInfoKey = 7; UIKeyboardAnimationDurationUserInfoKey = "0.25"; UIKeyboardBoundsUserInfoKey = "NSRect: {{0, 0}, {414, 271}}"; UIKeyboardCenterBeginUserInfoKey = "NSPoint: {207, 623}"; UIKeyboardCenterEndUserInfoKey = "NSPoint: {207, 600.5}"; UIKeyboardFrameBeginUserInfoKey = "NSRect: {{0, 510}, {414, 226}}"; UIKeyboardFrameEndUserInfoKey = "NSRect: {{0, 465}, {414, 271}}"; UIKeyboardIsLocalUserInfoKey = 1; } </code></pre> <p>键盘被遮挡了。</p> <p>总结:观察结果,发现了这个规律，打印一下时间,还有一个问题就是，中文键盘第一次启动的时候会回调两次。</p> <pre> <code class="language-objectivec">keyboardRect = [self.view convertRect:keyboardRect fromView:nil]; </code></pre> <p>所以去掉这句话即可</p> <h3><strong>六. 使用封装的XXTextField</strong></h3> <p>UITextView , UITextfield 中如果有keyboard的时候，需要一个自动弹起事件，以及弹起之后的content的偏移对父view的处理。如果每个页面都实现一次会非常复杂。这里我们介绍一种自动化的处理机制。在此之前，先介绍一下文字处理框架.最后给大家推荐一下我写的 XXTextField ,大家也可以在此基础上自己添加一些正则表达式。使用方法很简单.欢迎加入QQ群：237305299 ，一起探讨iOS技术问题</p> <p><strong>1.解决uiview中的textfield 遮挡问题</strong></p> <pre> <code class="language-objectivec">_textfieldName.keyboardType = UIKeyboardTypeDefault; _textfieldName.inputType = XXTextFieldTypeOnlyInt; _textfieldName.maxLength = 5; _textfieldPwd.inputType = XXTextFieldTypeForbidEmoj; #import "XXKeyboardManager.h" @interface XXCorrectVC ()<XXKeyboardManagerShowHiddenNotificationDelegate> @end @implementation XXCorrectVC - (void)viewDidLoad { [super viewDidLoad]; [[XXKeyboardManager sharedInstance] setDelegate:self]; // Do any additional setup after loading the view from its nib. } #pragma mark- KeyBoardShow/Hidden - (void)showKeyboardWithRect:(CGRect)keyboardRect withDuration:(CGFloat)animationDuration { CGFloat offset = self.textFieldCorrect.frame.size.height + self.textFieldCorrect.frame.origin.y - keyboardRect.origin.y; if(offset < 0){ return; } [UIView animateWithDuration:animationDuration delay:0.f options:UIViewAnimationOptionCurveEaseInOut animations:^{ CGRect rect = CGRectMake(0.0f, -offset,self.view.frame.size.width,self.view.frame.size.height); self.view.frame = rect; } completion:^(BOOL finished) { }]; } - (void)hiddenKeyboardWithRect:(CGRect)keyboardRect withDuration:(CGFloat)animationDuration { [UIView animateWithDuration:animationDuration delay:0.f options:UIViewAnimationOptionCurveEaseInOut animations:^{ self.textFieldCorrect.frame = self.view.bounds; } completion:^(BOOL finished) { }]; } @end </code></pre> <p><strong>2.解决uitableview中键盘遮挡问题</strong></p> <pre> <code class="language-objectivec">/* * 键盘要显示的时候 */ - (void)showKeyboardWithRect:(CGRect)keyboardRect withDuration:(CGFloat)animationDuration{ CGSize kbSize = keyboardRect.size; UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbSize.height, 0.0); _baseTableView.contentInset = contentInsets; _baseTableView.scrollIndicatorInsets = contentInsets; // If active text field is hidden by keyboard, scroll it so it's visible // Your app might not need or want this behavior. CGRect aRect = self.view.frame; aRect.size.height -= kbSize.height; if (!CGRectContainsPoint(aRect, _activeCell.frame.origin) ) { [_baseTableView scrollRectToVisible:_activeCell.frame animated:YES]; } } /* * 键盘要消失的时候 */ - (void)hiddenKeyboardWithRect:(CGRect)keyboardRect withDuration:(CGFloat)animationDuration{ _baseTableView.contentInset = UIEdgeInsetsZero; _baseTableView.scrollIndicatorInsets = UIEdgeInsetsZero; } </code></pre> <p> </p> <p>来自：http://www.iosxxx.com/blog/2016-11-27-UITextField最大字符数和最大字节数的限制.html</p> <p> </p>