ios開發之--通過通知監聽textfield的輸入狀態，判斷按鈕的狀態

標籤：註冊   selector   通過   events   uitext   tar   obj   change   state   

第一步：

_rightBtn = [UIButton buttonWithType:UIButtonTypeCustom];    _rightBtn.frame = CGRectMake(kWidth - 50-5, 7, kWidth - _tf.frame.size.width-10, 45);    [_rightBtn setBackgroundImage:[UIImage imageNamed:@"send_un"] forState:UIControlStateNormal];    [_rightBtn addTarget:self action:@selector(btnClick:) forControlEvents:UIControlEventTouchUpInside];    [_inputView addSubview:_rightBtn];

第二步：

    //監聽textfield的輸入狀態    [[NSNotificationCenter defaultCenter] addObserver:self                                             selector:@selector(textFieldDidChangeValue:)                                                 name:UITextFieldTextDidChangeNotification                                               object:_tf];

第三步：

//這裡可以通過發送object訊息擷取註冊時指定的UITextField對象- (void)textFieldDidChangeValue:(NSNotification *)notification{    UITextField *sender = (UITextField *)[notification object];    if(sender.text.length != 0)    {        [_rightBtn setBackgroundImage:[UIImage imageNamed:@"send"] forState:UIControlStateNormal];    }else    {        [_rightBtn setBackgroundImage:[UIImage imageNamed:@"send_un"] forState:UIControlStateNormal];    }}

和簡單，僅做記錄！

ios開發之--通過通知監聽textfield的輸入狀態，判斷按鈕的狀態