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UITextField最大字符数和最大字节数的限制

UITextView,UITextfield中有很多坑,网上的方法也很多,但是用过之后暂时没有发现一个好用。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

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- (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

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2. 推荐方法

使用rangeOfComposedCharacterSequencesForRange, 防止在range范围内整词被截断.因为中文的UTF8是3字节,Emoj是4个字节,且不能边输入边限制,否则中文联想的时候就无法继续输入。只能输入后在textfieldchange的时候进行截断。
综上所述,思路如下:

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- (void)textFieldDidChange:(UITextField *)textField
{
NSString *text = textField.text;
// NSLog(@"text:%@",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){
//---字符处理
if (text.length > _maxLength){
//中文和emoj表情存在问题,需要对此进行处理
NSRange range;
NSUInteger inputLength = 0;
for(int i=0; i < text.length && inputLength <= _maxLength; i += range.length) {
range = [textField.text rangeOfComposedCharacterSequenceAtIndex:i];
inputLength += [text substringWithRange:range].length;
if (inputLength > _maxLength) {
NSString* newText = [text substringWithRange:NSMakeRange(0, range.location)];
textField.text = newText;
}
}
}
}
}

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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

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- (void)textFieldDidChange:(UITextField *)textField
{
NSString *text = textField.text;
// NSLog(@"text:%@",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){
//---字节处理
//Limit
NSUInteger textBytesLength = [textField.text lengthOfBytesUsingEncoding:NSUTF8StringEncoding];
if (textBytesLength > _maxBytesLength) {
NSRange range;
NSUInteger byteLength = 0;
for(int i=0; i < text.length && byteLength <= _maxBytesLength; i += range.length) {
range = [textField.text rangeOfComposedCharacterSequenceAtIndex:i];
byteLength += strlen([[text substringWithRange:range] UTF8String]);
if (byteLength > _maxBytesLength) {
NSString* newText = [text substringWithRange:NSMakeRange(0, range.location)];
textField.text = newText;
}
}
}
}
if (self.textFieldChange) {
self.textFieldChange(self,textField.text);
}
}

三. 放弃键盘

1. 能拿到uitextfield的时候用

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- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
return [textField resignFirstResponder];
}

2. 点击view消失的时候用

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[self.view endEditing:YES];

3. 难以获取的时候用

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[[UIApplication sharedApplication] sendAction:@selector(resignFirstResponder) to:nil from:nil forEvent:nil];

或者

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[[[UIApplication sharedApplication] keyWindow] endEditing:YES];

2.Tableview点击空白处或者滚动时消失

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{
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

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-(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

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- (void)keyboardWillShow:(NSNotification *)notification {

NSDictionary *userInfo = [notification userInfo];

NSValue* aValue = http://www.mamicode.com/[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 = http://www.mamicode.com/[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

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打印userinfo:

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(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:

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打印userinfo:

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(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。

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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。使用方法很简单.欢迎加入QQ群:237305299 ,一起探讨iOS技术问题

1.解决uiview中的textfield 遮挡问题

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_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

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/*
* 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];
}http://www.90168.org/
}

/*
* 键盘要消失的时候
*/
- (void)hiddenKeyboardWithRect:(CGRect)keyboardRect
withDuration:(CGFloat)animationDuration{
_baseTableView.contentInset = UIEdgeInsetsZero;
_baseTableView.scrollIndicatorInsets = UIEdgeInsetsZero;
}

UITextField最大字符数和最大字节数的限制