【ios 异常FAQ】unrecognized selector sent to instance

unrecognized selector sent to instance 异常，一般是因为发送到消息对象被释放或者方法参数不匹配导致，因为@selector(XXX)在编译的时候没有明确现在参数类型；
一般在xcode中如何调试的时候直接定位到代码行，先设置 NSZombieEnabled为true，重新编译启动会直接定位到行。

eg：

self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"Show" style:0 target:self action:@selector(toggleAuthCodeBox:)];

- (void)toggleAuthCodeBox:(UIButton *)button   //这里应该为UIBarButtonItem，被强转，然后因为它没有setTitle：forState：方法导致；
{
self.loginBox.authCodeBoxVisible = !self.loginBox.authCodeBoxVisible;
[button setTitle:self.loginBox.authCodeBoxVisible ? @"Hide" : @"Show" forState:UIControlStateNormal];
}

正确的这么改：

self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"Show" style:0 target:self action:@selector(toggleAuthCodeBox:)];

- (void)toggleAuthCodeBox:(UIBarButtonItem *)button   //这里改为UIBarButtonItem
{
self.loginBox.authCodeBoxVisible = !self.loginBox.authCodeBoxVisible;
[button setTitle:self.loginBox.authCodeBoxVisible ? @"Hide" : @"Show"];  //这里改

}