iphone之按照教程中的说明调用FBSession.activeSession会导致NSException

我正在尝试在我的iPhone应用程序中启用Facebook登录。

我正在按照此页面上的说明进行操作:
https://developers.facebook.com/docs/howtos/login-with-facebook-using-ios-sdk/#step4

我已按照步骤4(登录Facebook)中的说明进行操作，但是运行该程序时代码崩溃。

这是导致崩溃的我的方法:

- (void)applicationDidBecomeActive:(UIApplication *)application 
{ 
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface. 
 
    // We need to properly handle activation of the application with regards to Facebook Login 
    // (e.g., returning from iOS 6.0 Login Dialog or from fast app switching). 
    NSLog(@"here 1"); 
    NSLog(@"active session: %@",FBSession.activeSession); 
    [FBSession.activeSession handleDidBecomeActive]; 
    NSLog(@"here 2"); 
} 

2013-02-11 17:31:17.956 TRIO[9426:907] here 1 
* thread #1: tid = 0x2503, 0x324d9960 libobjc.A.dylib`objc_exception_throw, stop reason = breakpoint 1.1 
frame #0: 0x324d9960 libobjc.A.dylib`objc_exception_throw 
frame #1: 0x3161af98 CoreFoundation`-[NSException raise] + 8 
frame #2: 0x0009f7cc XXX`-[FBSession initWithAppID:permissions:defaultAudience:urlSchemeSuffix:tokenCacheStrategy:] + 240 at FBSession.m:236 
frame #3: 0x0009f6d6 XXX`-[FBSession initWithAppID:permissions:urlSchemeSuffix:tokenCacheStrategy:] + 46 at FBSession.m:208 
frame #4: 0x0009f680 XXX`-[FBSession init] + 32 at FBSession.m:191 
frame #5: 0x000a061a XXX`+[FBSession activeSession] + 62 at FBSession.m:568 
frame #6: 0x00073c4e XXX`-[AppDelegate applicationDidBecomeActive:] + 66 at AppDelegate.m:118 
frame #7: 0x38e3bae2 UIKit`-[UIApplication _stopDeactivatingForReason:] + 342 
frame #8: 0x38e219b8 UIKit`-[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 1072 
frame #9: 0x38dc9c38 UIKit`-[UIApplication handleEvent:withNewEvent:] + 1004 
frame #10: 0x38dc96cc UIKit`-[UIApplication sendEvent:] + 72 
frame #11: 0x38dc911a UIKit`_UIApplicationHandleEvent + 6154 
frame #12: 0x393605a2 GraphicsServices`_PurpleEventCallback + 590 
frame #13: 0x393601d2 GraphicsServices`PurpleEventCallback + 34 
frame #14: 0x315f0172 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 34 
frame #15: 0x315f0116 CoreFoundation`__CFRunLoopDoSource1 + 138 
frame #16: 0x315eef98 CoreFoundation`__CFRunLoopRun + 1384 
frame #17: 0x31561ebc CoreFoundation`CFRunLoopRunSpecific + 356 
frame #18: 0x31561d48 CoreFoundation`CFRunLoopRunInMode + 104 
frame #19: 0x38e2047c UIKit`-[UIApplication _run] + 668 
frame #20: 0x38e1d2f8 UIKit`UIApplicationMain + 1120 
frame #21: 0x00073748 XXX`main + 96 at main.m:16 

请您参考如下方法:

我遇到了与上述相同的错误，这是因为我没有将自己的FacebookAppID以及“URL类型”键添加到项目的info.plist中