前言
這里我給大家幾組測試用例可以一試，為啥不好用。
1、限制10個字節，輸入2個Emoj之后是8個字節(一個Emoj是4個字節)，此時再輸入一個中文，看看結果如何(中文的UTF8占3個字節)
2、限制5個字符,一個Emoj是2個字符,其他都是一個。此時輸入兩個Emoj，再輸入中文，然后中文聯想試試。
就目前的情況來說，看了很多資料，并沒有一個通用的能限制字符數和字節數的封裝。這里全面進行了總結，并進行了封裝。歡迎大家下載。
一. 字符限制
1. 錯誤方法
常見的這種方法是錯誤的，會導致Emoj表情的截取問題
- (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;}這種限制方法會導致拼音下出現這種情況，且無法輸入.無法輸入滿5個字符。在emoj表情也有問題
2. 推薦方法
使用rangeOfComposedCharacterSequencesForRange, 防止在range范圍內整詞被截斷
- (void)textFieldDidChange:(UITextField *)textField{ NSString *toBeString = textField.text; UITextRange *selectedRange = [textField markedTextRange]; UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0]; // 沒有高亮選擇的字，則對已輸入的文字進行字數統計和限制,防止中文被截斷 if (!position){ if (toBeString.length > _maxLength){ //中文和emoj表情存在問題，需要對此進行處理 NSRange rangeRange = [toBeString rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, _maxLength)]; textField.text = [toBeString substringWithRange:rangeRange]; } }}
二. 字節限制
1. 限制字節數
在UTF8中，英文和數字是1個字節,漢子是3個字節，emoji是3或者4個字節。這里的難度比上面更大，如果截取失敗，極有可能出現亂碼。這里我們的做法如下
- (void)textFieldDidChange:(UITextField *)textField{ NSString *toBeString = textField.text; //---字節處理 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]; //限制字節數 if ([inputString length] > 0){ NSInteger len = strlen([inputString UTF8String]); if (len > _maxBytesLength){ return NO; } else { return YES; } } return YES;}這里不能只在進行限制，在textFieldDidChange中需要對中文聯想做處理才行
三. 放棄鍵盤
1. 能拿到uitextfield的時候用
- (BOOL)textFieldShouldReturn:(UITextField *)textField{ return [textField resignFirstResponder];}2. 點擊view消失的時候用
[self.view endEditing:YES];
3. 難以獲取的時候用
[[UIApplication sharedApplication] sendAction:@selector(resignFirstResponder) to:nil from:nil forEvent:nil];
或者
[[[UIApplication sharedApplication] keyWindow] endEditing:YES];
4.Tableview點擊空白處或者滾動時消失
{ UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(fingerTapped:)]; [self.view addGestureRecognizer:singleTap];}#pragma mark- 鍵盤消失-(void)fingerTapped:(UITapGestureRecognizer *)gestureRecognizer{ [self.view endEditing:YES];}-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{ [self.view endEditing:YES];}四. 正則表達式限制
請參考 正則表達式語法表 ,這里我提供了兩種表達式給大家參考，一個Int,一個無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的鍵盤事件多次回調問題
1.鍵盤高度遮擋問題
一般出現遮擋的時候我們用以下代碼,看看當前textfield是否在鍵盤下面，在的話算出鍵盤的頂端和textfield的底部的距離，然后做偏移動畫
- (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、真機
如果使用了中文輸入法，注冊的keyboardWillShow會回調兩次。第一次是鍵盤默認高度216，第二次則是加了keyboard的導航欄的高度。
2、模擬器
第一次彈出鍵盤沒有問題
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;}此時我們去按123旁邊的小圓球會出現如下的圖：
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;}鍵盤被遮擋了。
總結:觀察結果,發現了這個規律，打印一下時間,還有一個問題就是，中文鍵盤第一次啟動的時候會回調兩次。
keyboardRect = [self.view convertRect:keyboardRect fromView:nil];
所以去掉這句話即可
六. 使用封裝的XXTextField
UITextView , UITextfield 中如果有keyboard的時候，需要一個自動彈起事件，以及彈起之后的content的偏移對父view的處理。如果每個頁面都實現一次會非常復雜。這里我們介紹一種自動化的處理機制。在此之前，先介紹一下文字處理框架.最后給大家推薦一下我寫的 XXTextField ,大家也可以在此基礎上自己添加一些正則表達式。
1.解決uiview中的textfield 遮擋問題
_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) { }];}@end2.解決uitableview中鍵盤遮擋問題
/* * 鍵盤要顯示的時候 */- (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]; }}/* * 鍵盤要消失的時候 */- (void)hiddenKeyboardWithRect:(CGRect)keyboardRect withDuration:(CGFloat)animationDuration{ _baseTableView.contentInset = UIEdgeInsetsZero; _baseTableView.scrollIndicatorInsets = UIEdgeInsetsZero;}總結
以上就是這篇文章的全部內容了，希望本文的內容對各位Android開發者們能有所幫助，如果有疑問大家可以留言交流。
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