Using UITextField to restrict only Chinese, English, and numbers

Preface

This article mainly introduces the useUITextFieldLimits can only enter Chinese, English, and numbers, we can useNSPredicateRegular expressions can be filtered, let’s take a look at the detailed steps and methods below

First set the proxy of UItextField

Implement the following method:

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{

 if ([self isInputRuleAndNumber:string] || [string isEqualToString:@""]) {
  return YES;
 }
 return NO;
}

Then add events because the input method associative words will not passtextField:shouldChangeCharactersInRange:replacementString:Method

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

accomplish:

- (void)textFieldChanged:(UITextField *)textField {

 NSString *toBeString = ;
 NSString *lastString;
 if(>0)
  lastString=[toBeString substringFromIndex:-1];

 if (![self isInputRuleAndNumber:toBeString]&&[self hasEmoji:lastString]) {
   = [self disable_emoji:toBeString];
  return;
 }
 NSString *lang = [[textField textInputMode] primaryLanguage];
 if([lang isEqualToString:@"zh-Hans"]) {
  UITextRange *selectedRange = [textField markedTextRange];
  UITextPosition *position = [textField positionFromPosition: offset:0];
  if(!position) {
   NSString *getStr = [self getSubString:toBeString];
   if(getStr &&  > 0) {
     = getStr;
   }
  }
 } else{
  NSString *getStr = [self getSubString:toBeString];
  if(getStr &&  > 0) {
   = getStr;
  }
 }
}

Next, implement the restrictions:

In the pattern, enter the passed character that needs to be verified

Lowercase a-z

Capital A-Z

Chinese characters\u4E00-\u9FA5

Number\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;
}

Implement to determine whether it is 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;
}

Character limit

#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 ||  == 0) {
   data1 = [data subdataWithRange:NSMakeRange(0, kMaxLength - 1)];
   content = [[NSString alloc] initWithData:data1 encoding:encoding];
  }
  return content;
 }
 return nil;
}

Summarize

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