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
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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
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 ,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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