如何限制UITextField内输入的字数（很好很强大）

在输入东西的时候，如果想限制最大字数，可以用下面方法：

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

{

if ([string isEqualToString:@"\n"]){

return YES;

}

NSString * aString = [textField.text stringByReplacingCharactersInRange:range withString:string];

if (self.searchTextField == textField)

{

if ([aString length] > 5) {

textField.text = [aString substringToIndex:5];

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil

message:@"超过最大字数不能输入了"

delegate:nil

cancelButtonTitle:@"Ok"

otherButtonTitles:nil, nil];

[alert show];

[alert release];

return NO;

}

}

return YES;

}
转自http://blog.csdn.net/pjk1129/article/details/8469601