使用UITextField限制只可输入中,英文,数字的方法

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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:

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- (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

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[textField addTarget:self action:@selector(textFieldChanged:) forControlEvents:UIControlEventEditingChanged];

实现:

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- (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

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- (BOOL)isInputRuleAndNumber:(NSString *)str {
 NSString *pattern = @"[a-zA-Zu4E00-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

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- (BOOL)hasEmoji:(NSString*)str{
 NSString *pattern = @"[^\u0020-\u007E\u00A0-\u00BE\u2E80-\uA4CF\uF900-\uFAFF\uFE30-\uFE4F\uFF00-\uFFEF\u0080-\u009F\u2000-\u201frn]";
 NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", pattern];
 BOOL isMatch = [pred evaluateWithObject:str];
 return isMatch;
}

字符限制

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#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;
}