1.實(shí)時(shí)監(jiān)視文本變化
[textfield addTarget:self action:@selector(changed:) forControlEvents:UIControlEventEditingChanged];
//添加通知
[[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(textDidChange:)
                                                 name:UITextFieldTextDidChangeNotification
                                               object:nil];

2.代理方法
//首次點(diǎn)擊textField時(shí)調(diào)用,return no時(shí)不會(huì)輸出
- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField        // return NO to disallow editing.
{
    NSLog(@"---%@", textField.text);
    return YES;
}
//首次點(diǎn)擊textField時(shí)調(diào)用
- (void)textFieldDidBeginEditing:(UITextField *)textField           // became first responder
{
    NSLog(@"===%@", textField.text);
}
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string   // return NO to not change text
{
    //return no時(shí)輸入內(nèi)容無(wú)法改變
    //string:每次輸入的新字符串
    //range:range.location:新輸入字符串的位置, range.length:0
    NSLog(@"%lu, %lu", (unsigned long)range.location,(unsigned long)range.length);
    NSLog(@"%@", string);
    return YES;
}