ios - View 不能成为第一响应者

Question

我有一个 View Controller 。它由另一个 UINavigationController 推送。在 ViewController.m 中:

- (BOOL)canBecomeFirstResponder { 
    return YES;
}

- (void)viewDidAppear:(BOOL)animated {
    [self.view becomeFirstResponder];
    NSLog(@"%d", [self.view isFirstResponder]);
    [super viewDidAppear:animated];
}

它总是 0。为什么？

Answer 1

您的 View 必须接受第一响应者状态。这是在您的 View 的子类代码中实现的，您必须覆盖canBecomeFirstResponder并返回YES:

- (BOOL)canBecomeFirstResponder 
{ 
    return YES; 
}