ios - 我如何测试为什么该对象在没有返回时返回零？

Question

在Stackoverflow上搜索之后，我无法找到所需解决方案的重复问题，并且直到最近，此代码仍然可以正常工作，这是来自调试控制台的堆栈跟踪:

2016-10-10 17:01:27.873567 Eboticon[1628:411719] [DYMTLInitPlatform] platform initialization successful
2016-10-10 17:01:28.042711 Eboticon[1628:411555] Not purchased: com.eboticon.Eboticon.ratchpack3
2016-10-10 17:01:28.042838 Eboticon[1628:411555] Not purchased: com.eboticon.Eboticon.greetingspack1
2016-10-10 17:01:28.042902 Eboticon[1628:411555] Not purchased: com.eboticon.Eboticon.baepack1
2016-10-10 17:01:28.042959 Eboticon[1628:411555] Not purchased: com.eboticon.Eboticon.ratchpack1
2016-10-10 17:01:28.043014 Eboticon[1628:411555] Not purchased: com.eboticon.Eboticon.churchpack1
2016-10-10 17:01:28.043068 Eboticon[1628:411555] Not purchased: com.eboticon.Eboticon.greekpack2
2016-10-10 17:01:28.043122 Eboticon[1628:411555] Not purchased: com.eboticon.Eboticon.ratchpack2
2016-10-10 17:01:28.043176 Eboticon[1628:411555] Not purchased: com.eboticon.Eboticon.churchpack2
warning: could not load any Objective-C class information. This will significantly reduce the quality of type information available.
2016-10-10 17:06:16.186456 Eboticon[1628:411555] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSArrayM insertObject:atIndex:]: object cannot be nil'
*** First throw call stack:
(0x18f5b41c0 0x18dfec55c 0x18f493ad4 0x1000ec6d8 0x1000eb7ec 0x19546e61c 0x19567ed60 0x195684ad0 0x195699270 0x195681ab4 0x191155904 0x191155770 0x191155b18 0x18f562278 0x18f561bc0 0x18f55f7c0 0x18f48e048 0x1954677cc 0x195462550 0x100118f9c 0x18e4705b8)
libc++abi.dylib: terminating with uncaught exception of type NSException

添加异常断点时，它指向此行代码是问题所在:

[arrImagePagerImages addObject:[UIImage imageWithData:data]];

这是完整的代码库，最后有问题的代码:

#import "AppDelegate.h"
#import "JMCategoriesData.h"
#import "MasterViewController.h"
#import "GAI.h"
#import "GAIFields.h"
#import "iRate.h"
#import "DDLog.h"
#import "DDTTYLogger.h"
#import "Harpy.h"
#import "Constants.h"
#import <Fabric/Fabric.h>
#import <Crashlytics/Crashlytics.h>
#import <Parse/Parse.h>
#import "SWRevealViewController.h"
#import "RightViewController.h"
#import "XOSplashVideoController.h"

#define UIColorFromRGB(rgbValue) [UIColor colorWithRed:((float)((rgbValue & 0xFF0000) >> 16))/255.0 green:((float)((rgbValue & 0xFF00) >> 8))/255.0 blue:((float)(rgbValue & 0xFF))/255.0 alpha:1.0]


@interface AppDelegate()<SWRevealViewControllerDelegate>
@end

@implementation AppDelegate


#pragma mark -
#pragma mark AppDelegate Methods

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{

    // Register for Push Notitications
    UIUserNotificationType userNotificationTypes = (UIUserNotificationTypeAlert |
                                                    UIUserNotificationTypeBadge |
                                                    UIUserNotificationTypeSound);
    UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:userNotificationTypes
                                                                             categories:nil];
    [application registerUserNotificationSettings:settings];
    [application registerForRemoteNotifications];

    //[self showSplashVideo];

    //PARSE
    //[Parse setApplicationId:@"gBcNi8fexXd1Uiggm6e2hRFuOPkoEefsbxLDNzO7"
                  //clientKey:@"dKZXWc9CXdksCA7HPVSCp0Yz0tTBQuqnQEvXKwL6"];
    [PFAnalytics trackAppOpenedWithLaunchOptions:launchOptions];

    [self initialize];
    // Override point for customization after application launch.
    return YES;

}

/**
 *  Setup iRate rating scheme
 */
- (void) configureiRate
{
    @try {

        [iRate sharedInstance].appStoreID = appStoreID;


        [iRate sharedInstance].daysUntilPrompt = 10;
        [iRate sharedInstance].usesUntilPrompt = 5;
        //[iRate sharedInstance].verboseLogging = YES;
        [iRate sharedInstance].promptAtLaunch = YES;
        [iRate sharedInstance].eventsUntilPrompt = 5;
        [iRate sharedInstance].promptForNewVersionIfUserRated = YES;
        [iRate sharedInstance].remindPeriod = 7;
        //TODO: Set below to no before deploying!
        [iRate sharedInstance].previewMode = NO;

        DDLogInfo(@"%@: Number of events until iRate launch %lu", NSStringFromClass(self.class), (unsigned long)[iRate sharedInstance].eventCount);

        DDLogInfo(@"%@: Number of iRate uses %lu", NSStringFromClass(self.class), (unsigned long)[iRate sharedInstance].usesCount);

        DDLogInfo(@"%@: Prompt for rating criteria met: %lu", NSStringFromClass(self.class), (unsigned long)[iRate sharedInstance].shouldPromptForRating);
    }
    @catch (NSException *exception) {
        DDLogError(@"[ERROR] in enabling iRate: %@", exception.description);
    }

}

- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken {
    // Store the deviceToken in the current installation and save it to Parse.
    PFInstallation *currentInstallation = [PFInstallation currentInstallation];
    [currentInstallation setDeviceTokenFromData:deviceToken];
    currentInstallation.channels = @[ @"global" ];
    [currentInstallation saveInBackground];
}

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo {
    [PFPush handlePush:userInfo];
}

- (void)applicationWillResignActive:(UIApplication *)application
{
    // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
    // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later. 
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}

- (void)applicationWillEnterForeground:(UIApplication *)application
{
    // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}

- (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.
}

- (void)applicationWillTerminate:(UIApplication *)application
{
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
}


#pragma mark -
#pragma mark Initialize

- (void) showSplashVideo {

    CGRect frame = [[UIScreen mainScreen] bounds];
    self.window = [[UIWindow alloc] initWithFrame:frame];

    NSLog(@"Screen Height %f", self.window.frame.size.height);

    NSString *portraitVideoName = @"EboticonIntroNEW640x960";
    NSString *portraitImageName = @"iphone640x960.png";
    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone && self.window.frame.size.height > 480) {
        portraitImageName = @"iphone640x1136.png";
        portraitVideoName = @"EboticonIntroNEW640x1136";
    }

    NSString *landscapeVideoName = nil; // n/a
    NSString *landscapeImageName = nil; // n/a
    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) {
        portraitVideoName = @"EboticonIntroNEW768x1024";
        portraitImageName = @"ipad768x1024.png";
        landscapeVideoName = @"EboticonIntroNEW768x1024.mp4";
        landscapeImageName = @"ipad768x1024.png";
    }

    // our video
    NSURL *portraitUrl = [[NSBundle mainBundle] URLForResource:portraitVideoName withExtension:@"mp4"];
    NSURL *landscapeUrl = [[NSBundle mainBundle] URLForResource:landscapeVideoName withExtension:@"mp4"];

    // our splash controller
    XOSplashVideoController *splashVideoController =
    [[XOSplashVideoController alloc] initWithVideoPortraitUrl:portraitUrl
                                            portraitImageName:portraitImageName
                                                 landscapeUrl:landscapeUrl
                                           landscapeImageName:landscapeImageName
                                                     delegate:self];
    // we'll start out with the spash view controller in the window
    self.window.rootViewController = splashVideoController;

    [self.window makeKeyAndVisible];

}

- (void) initialize {
    _products = nil;

    [[EboticonIAPHelper sharedInstance] requestProductsWithCompletionHandler:^(BOOL success, NSArray *products) {
        if (success) {
            _products = products;
            NSLog(@"--------DONE-------");
        }
    }];

    arrImagePagerImages = [[NSMutableArray alloc]init];

    for (NSInteger i = 1 ; i <= 4 ; i ++){
        NSString *sUrl = [NSString stringWithFormat:@"http://www.inclingconsulting.com/eboticon/store/banner%i.png", (int)i];
        NSData * data = [[NSData alloc] initWithContentsOfURL: [NSURL URLWithString: sUrl]];
        if (data == nil)continue;
        [arrImagePagerImages addObject:[UIImage imageWithData:data]];
    }

    //Setting up Navigation Bar
    [[UINavigationBar appearance] setBarTintColor:UIColorFromRGB(0x380063)];

    NSShadow *shadow = [[NSShadow alloc] init];
    shadow.shadowColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.8];
    shadow.shadowOffset = CGSizeMake(0, 1);
    [[UINavigationBar appearance] setTitleTextAttributes: [NSDictionary dictionaryWithObjectsAndKeys:
                                                           [UIColor colorWithRed:245.0/255.0 green:245.0/255.0 blue:245.0/255.0 alpha:1.0], NSForegroundColorAttributeName,
                                                           shadow, NSShadowAttributeName,
                                                           [UIFont fontWithName:@"Avenir-Black" size:21.0], NSFontAttributeName, nil]];
    [[UINavigationBar appearance] setTintColor:UIColorFromRGB(0xFf6c00)]; //Color of back button

    //Tabbar With sidebar Items
    NSNumber *caption = @(1); //initialize caption to on
    self.tabBarController = [[TabViewController alloc] initWithCaption:caption];
    RightViewController *rightViewController = [[RightViewController alloc] init];
    SWRevealViewController *mainRevealController = [[SWRevealViewController alloc]
                                                    initWithRearViewController:rightViewController frontViewController:self.tabBarController];
    mainRevealController.rightViewController = rightViewController;
    mainRevealController.delegate = self;
    self.viewController = mainRevealController;

    //Add Tab Bar
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    //self.window.rootViewController = self.tabBarController;
    self.window.rootViewController = self.viewController;



    UIImageView *splashScreen = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Default.png"]];
    [self.window addSubview:splashScreen];
    [self.window makeKeyAndVisible];

    [UIView animateWithDuration:0.3 animations:^{splashScreen.alpha = 0.0;}
                     completion:(void (^)(BOOL)) ^{
                         [splashScreen removeFromSuperview];
                     }
     ];

    // Present Window before calling Harpy
    //[self.window makeKeyAndVisible];


    //GOOGLE ANALYTICS INITIALIZER
    // Optional: automatically send uncaught exceptions to Google Analytics.
    [GAI sharedInstance].trackUncaughtExceptions = YES;
    // Optional: set Google Analytics dispatch interval to e.g. 20 seconds.
    [GAI sharedInstance].dispatchInterval = 20;
    // Optional: set Logger to VERBOSE for debug information.
    [[[GAI sharedInstance] logger] setLogLevel:kGAILogLevelError];


    // Initialize tracker. Replace with your tracking ID.
#ifdef FREE
    [[GAI sharedInstance] trackerWithTrackingId:@"UA-48552713-3"];
    DDLogInfo(@"Google Analytics Enabled for Lite Version");
#else
    [[GAI sharedInstance] trackerWithTrackingId:@"UA-48552713-4"];
    DDLogInfo(@"Google Analytics Enabled for Paid Version");
#endif

    //Set dry run to yes for testing purposes
    [[GAI sharedInstance] setDryRun:NO];

    //Set version for app tracking
    NSString *version = [[NSBundle mainBundle] objectForInfoDictionaryKey:(NSString *)kCFBundleVersionKey];
    [[GAI sharedInstance].defaultTracker set:kGAIAppVersion value:version];
    [[GAI sharedInstance].defaultTracker set:kGAISampleRate value:@"50.0"];

    //Cocoalumberjack init files
    [DDLog addLogger:[DDTTYLogger sharedInstance]];
    [[DDTTYLogger sharedInstance] setColorsEnabled:YES];

    //configure iRate
    [self configureiRate];

    //Harpy
    //TODO: turn on Harpy
    [self configureHarpy];

    //FABRIC
    [Fabric with:@[CrashlyticsKit]];
}

/**
 *  Setup Harpy update reminder
 */
- (void) configureHarpy
{
    @try {

        // Set the App ID for your app
        #ifdef FREE
                [[Harpy sharedInstance] setAppID:@"977505283"];
        #else
                [[Harpy sharedInstance] setAppID:@"899011953"];
        #endif

                // Set the UIViewController that will present an instance of UIAlertController
                [[Harpy sharedInstance] setPresentingViewController:_window.rootViewController];

                // (Optional) The tintColor for the alertController
                //[[Harpy sharedInstance] setAlertControllerTintColor:@"<#alert_controller_tint_color#>"];

                // (Optional) Set the App Name for your app
        #ifdef FREE
                [[Harpy sharedInstance] setAppName:@"Eboticon Lite"];
        #else
                [[Harpy sharedInstance] setAppName:@"Eboticon"];
        #endif

        // Perform check for new version of your app
        [[Harpy sharedInstance] checkVersion];
    }
    @catch (NSException *exception) {
        DDLogError(@"[ERROR] in enabling Harpy: %@", exception.description);
    }



}


#pragma mark -
#pragma mark Reveal Controller Delegate

- (NSString*)stringFromFrontViewPosition:(FrontViewPosition)position
{
    NSString *str = nil;
    if ( position == FrontViewPositionLeft ) str = @"FrontViewPositionLeft";
    if ( position == FrontViewPositionRight ) str = @"FrontViewPositionRight";
    if ( position == FrontViewPositionRightMost ) str = @"FrontViewPositionRightMost";
    if ( position == FrontViewPositionRightMostRemoved ) str = @"FrontViewPositionRightMostRemoved";
    return str;
}

- (void)revealController:(SWRevealViewController *)revealController willMoveToPosition:(FrontViewPosition)position
{
    NSLog( @"%@: %@", NSStringFromSelector(_cmd), [self stringFromFrontViewPosition:position]);
}

- (void)revealController:(SWRevealViewController *)revealController didMoveToPosition:(FrontViewPosition)position
{
    NSLog( @"%@: %@", NSStringFromSelector(_cmd), [self stringFromFrontViewPosition:position]);
}

- (void)revealController:(SWRevealViewController *)revealController willRevealRearViewController:(UIViewController *)rearViewController
{
    NSLog( @"%@", NSStringFromSelector(_cmd));
}

- (void)revealController:(SWRevealViewController *)revealController didRevealRearViewController:(UIViewController *)rearViewController
{
    NSLog( @"%@", NSStringFromSelector(_cmd));
}

- (void)revealController:(SWRevealViewController *)revealController willHideRearViewController:(UIViewController *)rearViewController
{
    NSLog( @"%@", NSStringFromSelector(_cmd));
}

- (void)revealController:(SWRevealViewController *)revealController didHideRearViewController:(UIViewController *)rearViewController
{
    NSLog( @"%@", NSStringFromSelector(_cmd));
}

- (void)revealController:(SWRevealViewController *)revealController willShowFrontViewController:(UIViewController *)rearViewController
{
    NSLog( @"%@", NSStringFromSelector(_cmd));
}

- (void)revealController:(SWRevealViewController *)revealController didShowFrontViewController:(UIViewController *)rearViewController
{
    NSLog( @"%@", NSStringFromSelector(_cmd));
}

- (void)revealController:(SWRevealViewController *)revealController willHideFrontViewController:(UIViewController *)rearViewController
{
    NSLog( @"%@", NSStringFromSelector(_cmd));
}

- (void)revealController:(SWRevealViewController *)revealController didHideFrontViewController:(UIViewController *)rearViewController

{
    NSLog( @"%@", NSStringFromSelector(_cmd));
}


#pragma mark Splash Video

- (void)splashVideoLoaded:(XOSplashVideoController *)splashVideo
{
    // load up our real view controller, but don't put it in to the window until the video is done
    // if there's anything expensive to do it should happen in the background now

   //

   // self.viewController = [[XOViewController alloc] initWithNibName:@"XOViewController" bundle:nil];
}

- (void)splashVideoComplete:(XOSplashVideoController *)splashVideo
{
    // swap out the splash controller for our app's
    //self.window.rootViewController = self.viewController;
    [self initialize];
}
@end

当我们注释掉有问题的行时，该应用程序可以正常运行，但不会显示所需的数组。当我执行数组的NSLog时，它将显示对象的地址。关于为什么它不会显示对象并且系统认为它为零的任何建议？

Answer 1

如果提供的数据无法转换为图像，则[UIImage imageWithData:]可能返回nil。如果发生这种情况，那么您将得到异常，因为您是将结果添加到数组而不进行检查，并且NSMutableArray不能包含nil。

您应该单独转换图像，并且仅将其添加到数组中(如果非nil):

UIImage *image = [UIImage imageWithData:data];
if (image != nil) {
    [arrImagePagerImages addObject:image];
} else {
    NSLog(@"Unable to convert data to image");
}