前言
这里我给大家几组测试用例可以一试，为啥不好用。
1、限制10个字节，输入2个Emoj之后是8个字节(一个Emoj是4个字节)，此时再输入一个中文，看看结果如何(中文的UTF8占3个字节)
2、限制5个字符,一个Emoj是2个字符,其他都是一个。此时输入两个Emoj，再输入中文，然后中文联想试试。
就目前的情况来说，看了很多资料，并没有一个通用的能限制字符数和字节数的封装。这里全面进行了总结，并进行了封装。欢迎大家下载。
一. 字符限制
1. 错误方法
常见的这种方法是错误的，会导致Emoj表情的截取问题
- (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; }
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
2. 推荐方法
使用rangeOfComposedCharacterSequencesForRange, 防止在range范围内整词被截断
- (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]; } } }
二. 字节限制
1. 限制字节数
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
- (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; }
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
三. 放弃键盘
1. 能拿到uitextfield的时候用
- (BOOL)textFieldShouldReturn:(UITextField *)textField { return [textField resignFirstResponder]; }
2. 点击view消失的时候用
[self.view endEditing:YES];
3. 难以获取的时候用
[[UIApplication sharedApplication] sendAction:@selector(resignFirstResponder) to:nil from:nil forEvent:nil];
或者
[[[UIApplication sharedApplication] keyWindow] endEditing:YES];
4.Tableview点击空白处或者滚动时消失
{ 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]; }
四. 正则表达式限制
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
-(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]+"]; }
五. UITextfield的键盘事件多次回调问题
1.键盘高度遮挡问题
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
- (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]; } }
1、真机
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。
2、模拟器
第一次弹出键盘没有问题
打印userinfo:
(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; }
此时我们去按123旁边的小圆球会出现如下的图：
打印userinfo:
(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; }
键盘被遮挡了。
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。
keyboardRect = [self.view convertRect:keyboardRect fromView:nil];
所以去掉这句话即可
六. 使用封装的XXTextField
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。
1.解决uiview中的textfield 遮挡问题
_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
2.解决uitableview中键盘遮挡问题
/* * 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; }
总结
以上就是这篇文章的全部内容了，希望本文的内容对各位Android开发者们能有所帮助，如果有疑问大家可以留言交流。
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