加載presentModalViewController導致EXC_BAD_ACCESS

在Follwoing ViewControllerClass我在嘗試調用presentModalViewController在ViewDidAppear方法時EXC_BAD_ACCESS。加載presentModalViewController導致EXC_BAD_ACCESS

#import "SounderViewController.h" 
#import "ASIFormDataRequest.h" 
#import "ASIHTTPRequest.h" 
#import "JSON.h" 
#import "InfoViewController.h" 


@implementation SounderViewController 

@synthesize ipod; 
@synthesize ivc; 
@synthesize title_lb, artist_lb, check; 

-(IBAction)showCurrentSongInfo{ 

    MPMediaItem * song = [ipod nowPlayingItem]; 
    NSString * title = [song valueForProperty:MPMediaItemPropertyTitle]; 
    NSString * artist = [song valueForProperty:MPMediaItemPropertyArtist]; 


    title_lb.text = title; 
    artist_lb.text = artist; 
} 

-(void)playbackStateChanged: (NSNotification*) notification{ 
    [self showCurrentSongInfo]; 
    NSLog(@"Playback state: %@",[notification name]); 
    if (ipod.playbackState != MPMusicPlaybackStatePlaying) { 
     NSLog(@"Is not playing"); 
     [self presentModalViewController:self.ivc animated:YES]; 
    }else if (ipod.playbackState == MPMusicPlaybackStatePlaying) { 
     NSLog(@"Is playing"); 
     [self dismissModalViewControllerAnimated:YES]; 
    } 
} 

-(void)nowPlayingItemChanged: (NSNotification*) notification{ 
    [self showCurrentSongInfo]; 
    NSLog(@"Playing item changed: %@",[notification name]); 
} 

- (void)viewDidLoad { 
    [super viewDidLoad]; 

    self.ivc = [[InfoViewController alloc] initWithNibName:@"InfoViewController" bundle:nil]; 

    self.ipod = [MPMusicPlayerController iPodMusicPlayer]; 


    [[NSNotificationCenter defaultCenter] addObserver:self 
              selector:@selector (playbackStateChanged:) 
               name:@"MPMusicPlayerControllerPlaybackStateDidChangeNotification" 
               object:nil]; 

    [[NSNotificationCenter defaultCenter] addObserver:self 
              selector:@selector (nowPlayingItemChanged:) 
               name:@"MPMusicPlayerControllerNowPlayingItemDidChangeNotification" 
               object:nil]; 
    [[MPMusicPlayerController iPodMusicPlayer] beginGeneratingPlaybackNotifications]; 

} 

-(void)viewDidAppear:(BOOL)animated{ 
    [super viewDidAppear:animated]; 

    if (ipod.playbackState != MPMusicPlaybackStatePlaying) { 
     [self presentModalViewController:self.ivc animated:YES]; 
    }else{ 
     [self showCurrentSongInfo]; 
    } 
} 

-(IBAction)showInfoView{ 
    [self presentModalViewController:self.ivc animated:YES]; 
} 



#pragma mark View Methods 

- (void)didReceiveMemoryWarning { 
    // Releases the view if it doesn't have a superview. 
    [super didReceiveMemoryWarning]; 

    // Release any cached data, images, etc that aren't in use. 
} 

- (void)viewDidUnload { 
    // Release any retained subviews of the main view. 
    // e.g. self.myOutlet = nil; 
} 


- (void)dealloc { 
    [super dealloc]; 
} 

@end

方法調用

[self presentModalViewController:self.ivc animated:YES];

在ViewDidAppear

導致EXC_BAD_ACCESS。

我試圖與NSZombieEnabled調試運行，但只拿到了一組調用主。讓我瘋狂的事情是，如果從方法playbackStateChanged運行相同的代碼，它工作正常。

如果你們能幫助我wan't獲得大膽快。謝謝。

來源

2010-02-19 Cyprian

您是否使用retain或copy屬性聲明瞭ivc（不是一個好的屬性名稱）？如果不是，退出loadView時不會保留，這就是你的問題。 – Felixyz 2010-02-19 14:33:01

是的，我就與reatain財產申報IVC：@property（非原子，保留）InfoViewController * IVC; – Cyprian 2010-02-19 15:02:45

我終於做到了工作！但我認爲這只是快速修復。

於是我發現，使我IVC展現出來，我需要調用耽誤presentModalViewController

[self performSelector:@selector(showWaitingMessageView:) withObject:self.ivc afterDelay:1];

就是這樣。有用。

我不知道爲什麼會幫助，所以如果你大師一個人知道更多關於它請賜教。

來源

2010-02-19 21:32:49 Cyprian

我有同樣的問題，它在我的iPhone 2G iOS 3.1.2上崩潰，並且不會在模擬器中崩潰。我猜這個解決方案工作的原因是因爲一些動畫機制仍然發生在viewDidAppear之後：並執行performSelector：withObject：afterDelay：推遲到下一個消息循環的調用 - 在我的情況下，即使延遲= 0也可以。 – Anton 2010-11-17 13:56:19

加載presentModalViewController導致EXC_BAD_ACCESS

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