以编程方式创建的视图崩溃

Question

Patients: Two controllers -- ViewController and (modally presented) RecorderViewController Symptoms: After the RecorderViewController is modally presented, it does some work. After being dismissed, the program crashes with EXC_BAD_ACCESS

In AppDelegate.m:

@synthesize window = _window;
@synthesize controller = _controller;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:    (NSDictionary *)launchOptions
{
    // Override point for customization after application launch.
    self.controller = [ViewController alloc];

    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.window.rootViewController = self.controller;
    [self.window makeKeyAndVisible];

    return YES;
}

In ViewController.m

#import "ViewController.h"
#import "RecorderViewController.h"

@interface ViewController ()

@end

@implementation ViewController

@synthesize presentModalButton;

- (void)loadView 
{
    self.view = [[UIView alloc] initWithFrame:[UIScreen mainScreen].applicationFrame];

    self.presentModalButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    self.presentModalButton.frame = CGRectMake(0, self.view.frame.size.height/2, 100, 50);
    [self.presentModalButton addTarget:self action:@selector(goToRecorderButtonPressed:) forControlEvents:UIControlEventTouchUpInside];

    [self.view addSubview:self.presentModalButton];

}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (IBAction)goToRecorderButtonPressed:(id)sender {
    RecorderViewController *recorderVC = [RecorderViewController alloc];
    [self presentModalViewController:recorderVC animated:YES];
}

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    self.presentModalButton = nil;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

@end

Crashes in main.m at return UIApplicationMain: #import

#import "AppDelegate.h"

int main(int argc, char *argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}

Answer 1

I believe there is problem in goToRecorderButtonPressed method.

Look, you are allocating memory for a recorderVC but don't initing it. You should initialize your object with on of available methods, for example, init :

- (IBAction)goToRecorderButtonPressed:(id)sender {
    RecorderViewController *recorderVC = [[RecorderViewController alloc] init];
    [self presentModalViewController:recorderVC animated:YES];
}