使用UITextField限制只可输入中,英文,数字的方法

前言

本文主要介绍使用uitextfield限制只可输入中,英文,数字，我们可以使用nspredicate正则表达式可以过滤，下面看看详细的步骤方法

首先设置uitextfield的代理

实现如下方法:

- (bool)textfield:(uitextfield *)textfield shouldchangecharactersinrange:(nsrange)range replacementstring:(nsstring *)string{

 if ([self isinputruleandnumber:string] || [string isequaltostring:@""]) {
  return yes;
 }
 return no;
}

然后添加事件,因为选择输入法联想的词.是不会经过textfield:shouldchangecharactersinrange:replacementstring:方法的

 [textfield addtarget:self action:@selector(textfieldchanged:) forcontrolevents:uicontroleventeditingchanged];

实现:

- (void)textfieldchanged:(uitextfield *)textfield {

 nsstring *tobestring = textfield.text;
 nsstring *laststring;
 if(tobestring.length>0)
  laststring=[tobestring substringfromindex:tobestring.length-1];

 if (![self isinputruleandnumber:tobestring]&&[self hasemoji:laststring]) {
  textfield.text = [self disable_emoji:tobestring];
  return;
 }
 nsstring *lang = [[textfield textinputmode] primarylanguage];
 if([lang isequaltostring:@"zh-hans"]) {
  uitextrange *selectedrange = [textfield markedtextrange];
  uitextposition *position = [textfield positionfromposition:selectedrange.start offset:0];
  if(!position) {
   nsstring *getstr = [self getsubstring:tobestring];
   if(getstr && getstr.length > 0) {
    textfield.text = getstr;
   }
  }
 } else{
  nsstring *getstr = [self getsubstring:tobestring];
  if(getstr && getstr.length > 0) {
   textfield.text= getstr;
  }
 }
}

再来实现限制:

pattern中,输入需要验证的通过的字符

     小写a-z

     大写a-z

     汉字\u4e00-\u9fa5

     数字\u0030-\u0039

- (bool)isinputruleandnumber:(nsstring *)str {
 nsstring *pattern = @"[a-za-z\u4e00-\u9fa5\\u0030-\\u0039]";
 nspredicate *pred = [nspredicate predicatewithformat:@"self matches %@", pattern];
 bool ismatch = [pred evaluatewithobject:str];
 return ismatch;
}

实现判断是否是emoji

- (bool)hasemoji:(nsstring*)str{
 nsstring *pattern = @"[^\\u0020-\\u007e\\u00a0-\\u00be\\u2e80-\\ua4cf\\uf900-\\ufaff\\ufe30-\\ufe4f\\uff00-\\uffef\\u0080-\\u009f\\u2000-\\u201f\r\n]";
 nspredicate *pred = [nspredicate predicatewithformat:@"self matches %@", pattern];
 bool ismatch = [pred evaluatewithobject:str];
 return ismatch;
}

字符限制

#define kmaxlength 20;
-(nsstring *)getsubstring:(nsstring*)string
{
 nsstringencoding encoding = cfstringconvertencodingtonsstringencoding(kcfstringencodinggb_18030_2000);
 nsdata* data = [string datausingencoding:encoding];
 nsinteger length = [data length];
 if (length > kmaxlength) {
  nsdata *data1 = [data subdatawithrange:nsmakerange(0, kmaxlength)];
  nsstring *content = [[nsstring alloc] initwithdata:data1 encoding:encoding];
  if (!content || content.length == 0) {
   data1 = [data subdatawithrange:nsmakerange(0, kmaxlength - 1)];
   content = [[nsstring alloc] initwithdata:data1 encoding:encoding];
  }
  return content;
 }
 return nil;
}

总结

以上就是这篇文章的全部内容了，希望能对大家的学习或者工作带来一定的帮助，如果有疑问大家可以留言交流。