Objective-C从Superview中删除UIButton

Question

我在.h文件中定义了以下UIButton：

@property (nonatomic,strong) UIButton *loginButton;

- (void)LoginButtonPressed:(UIButton *)sender;

并在我的.m文件中创建它：

@synthesize loginButton;

loginButton = [UIButton buttonWithType:UIButtonTypeCustom];
[loginButton setFrame:CGRectMake(150.0f, 131.0f, 105.0f, 35.0f)];
[loginButton setBackgroundImage:[UIImage imageNamed:@"black_button.png"] forState:UIControlStateNormal];
[loginButton setTitle:@"Login" forState:UIControlStateNormal];
[loginButton setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
[loginButton addTarget:self action:@selector(LoginButtonPressed:) forControlEvents:UIControlEventTouchUpInside];

- (void)LoginButtonPressed:(UIButton *)sender
{
    [self CreateActivityIndicator];
    [self performSelector:@selector(Login) withObject:nil afterDelay:0.5];

}

并且我有一个名为login的方法，并且在登录时我想从超级视图中删除登录按钮。

[self.loginButton removeFromSuperview];

但是突然之间（截至昨天），我的应用开始崩溃，并在此行上引发了错误：

@property (nonatomic,strong) UIButton *loginButton;

Thread 1: EXC_BAD_ACCESS(code=1, address0x10000010)

为什么会这样呢？ 以及如何解决？ 昨天我确实更改了登录方式以使用AFNetworking，可以吗？

以防万一，这是我的完整方法：

- (void)Login
{
    NSString *rawString = [self.idTextField text];
    NSCharacterSet *whitespace = [NSCharacterSet whitespaceAndNewlineCharacterSet];
    [self.idTextField setText:[rawString stringByTrimmingCharactersInSet:whitespace]];

    [userName UserLogin:self.idTextField.text andPassWordExists:self.passwordTextField.text completionHandler:^(id responseObject, NSError *error) {
        if (responseObject) {
            [self.idTextField removeFromSuperview];
            [self.passwordTextField removeFromSuperview];
            [self.loginButton removeFromSuperview];
            self.idTextField = nil;
            self.passwordTextField = nil;
            self.loginButton = nil;
            [self CreateMenu];
        }else{
            [self CustomAlert:@"Sorry Login Failed, User and/or Passsword Incorrect"];
        }
    }];

    [indicatorView stopAnimating];
    [indicatorView removeFromSuperview];
    indicatorView = nil;
    [loadingView removeFromSuperview];
    loadingView = nil;

}

这是触发它的原因：

-(void)UserLogin:(NSString *)user andPassWordExists:(NSString *)password completionHandler:(void (^)(NSArray *resultsObject, NSError *error))completionHandler
{


   NSURL *url = [NSURL URLWithString:kIP];
   NSURLRequest *request = [NSURLRequest requestWithURL:url];

    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc]
                                         initWithRequest:request];


    NSURLCredential *credential = [NSURLCredential
                                   credentialWithUser:user
                                   password:password
                                   persistence:NSURLCredentialPersistenceForSession];

    [operation setCredential:credential];

    [[NSOperationQueue mainQueue] addOperation:operation];

    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {

        if (completionHandler) {
            completionHandler(responseObject, nil);
        }

    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {

        if (completionHandler) {
            completionHandler(nil, error);
        }

    }];

    [operation start];
}

这是我的按钮以及2个文本项被添加到视图的方式：

//add all controls to the loginView
        [loginMenuView addSubview:self.idTextField];
        [loginMenuView addSubview:self.passwordTextField];
        [loginMenuView addSubview:self.loginButton];

更新

通过执行以下操作，我能够解决此问题：

取出self.loginButton = nil; 从我的登录方法，所以它看起来像这样：

- (void)Login
{
    NSString *rawString = [self.idTextField text];
    NSCharacterSet *whitespace = [NSCharacterSet whitespaceAndNewlineCharacterSet];
    [self.idTextField setText:[rawString stringByTrimmingCharactersInSet:whitespace]];


    [userName UserLogin:self.idTextField.text andPassWordExists:self.passwordTextField.text completionHandler:^(id responseObject, NSError *error) {
        if (responseObject) {

                [self.idTextField removeFromSuperview];
                [self.passwordTextField removeFromSuperview];
                [self.loginButton removeFromSuperview];
                self.idTextField = nil;
                self.passwordTextField = nil;
                //self.loginButton = nil;


                [self CreateMenu];



                [indicatorView stopAnimating];
                [indicatorView removeFromSuperview];
                indicatorView = nil;
                [loadingView removeFromSuperview];
                loadingView = nil;
        }else{


            [self CustomAlert:@"Sorry Login Failed, User and/or Passsword Incorrect"];

            [indicatorView stopAnimating];
            [indicatorView removeFromSuperview];
            indicatorView = nil;
            [loadingView removeFromSuperview];
            loadingView = nil;

        }
    }];

}

并取出[self.loginButton removeFromSuperview]; 和self.loginButton = nil; 从我的viewWillDisappear方法像这样：

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    userName = nil;
    [[NSNotificationCenter defaultCenter]removeObserver:self];
    [self.idTextField removeFromSuperview];
    [self.passwordTextField removeFromSuperview];
    //[self.loginButton removeFromSuperview];
    [self.menu removeFromSuperview];
    [logoutButton removeFromSuperview];
    //set every control to nil
    self.idTextField = nil;
    self.passwordTextField = nil;
    //self.loginButton = nil;
    self.menu = nil;
    menuItems = nil;
    textfieldNavigatorView = nil;
}

这解决了我的问题，我只想知道这是否是最佳解决方案。

Answer 1

我认为正在发生的事情是您的loginButton与您的indicatorView或loadingView绑定在一起。

由于您使用的是完成处理程序，因此其中的代码将异步运行。 那意味着你

indicatorView = nil 

或你的

loadingView = nil

在删除loginButton之前被触发。 如果loginButton是这些视图之一的子视图，则不再有对其的引用，因此您将获得BAD_ACCESS。 确保将最后五行代码（处理loadingView和indicatorView的代码）放在完成处理程序中，如下所示：

- (void)Login
{
NSString *rawString = [self.idTextField text];
NSCharacterSet *whitespace = [NSCharacterSet whitespaceAndNewlineCharacterSet];
[self.idTextField setText:[rawString stringByTrimmingCharactersInSet:whitespace]];

[userName UserLogin:self.idTextField.text andPassWordExists:self.passwordTextField.text completionHandler:^(id responseObject, NSError *error) {
    if (responseObject) {


        [self.idTextField removeFromSuperview];
        [self.passwordTextField removeFromSuperview];
        //access the loginButton while it still has reference
        [self.loginButton removeFromSuperview];
        self.idTextField = nil;
        self.passwordTextField = nil;
        //access the loginButton while it still has reference
        self.loginButton = nil;

        //Then remove these views
        [indicatorView stopAnimating];
        [indicatorView removeFromSuperview];
        indicatorView = nil;
        [loadingView removeFromSuperview];
        loadingView = nil;

        [self CreateMenu];
    }else{
        [self CustomAlert:@"Sorry Login Failed, User and/or Passsword Incorrect"];
    }
}];

}