需求：限制UITextField只能输入中文，并且最大长度为4；
解决方案：直接上干货！
1，先声明一个UITextfield 变量；
@property (nonatomic, strong) UITextField *textField;
2，添加通知；
(void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textFiledEditChanged:)name:UITextFieldTextDidChangeNotification object:self.textField];
}
3，在监听中，实现过滤非中文字符，并限制字符数量；-
(BOOL)textFieldShouldReturn:(UITextField *)textField{
[textField resignFirstResponder];//过滤非汉字字符
textField.text = [self filterCharactor:textField.text withRegex:@"[^\u4e00-\u9fa5]"];if (textField.text.length >= 4) {
textField.text = [textField.text substringToIndex:4];}
return NO;
} -
(void)textFiledEditChanged:(id)notification{
UITextRange *selectedRange = self.textField.markedTextRange;
UITextPosition *position = [self.textField positionFromPosition:selectedRange.start offset:0];if (!position) { //// 没有高亮选择的字
//过滤非汉字字符
self.textField.text = [self filterCharactor:self.textField.text withRegex:@"[^\u4e00-\u9fa5]"];if (self.textField.text.length >= 4) { self.textField.text = [self.textField.text substringToIndex:4]; }}else { //有高亮文字
//do nothing
}
}
//根据正则，过滤特殊字符
- (NSString *)filterCharactor:(NSString *)string withRegex:(NSString *)regexStr{
NSString *searchText = string;
NSError *error = NULL;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:regexStr options:NSRegularExpressionCaseInsensitive error:&error];
NSString *result = [regex stringByReplacingMatchesInString:searchText options:NSMatchingReportCompletion range:NSMakeRange(0, searchText.length) withTemplate:@""];
return result;
}
4，Game over.
