使用UITextField限制只可输入中,英文,数字的方法
作者：辛多雷的挽歌
在我们日常开发中经常遇到一些情况，要UITextField只能输入某一种特定的字符.比如大写A-Z或者小写a-z,或者汉字.或者数字.那么该如何实现呢，下面通过这篇文章来看看吧。
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。