UIManagedDocument - 如何处理UIDocumentStateSavingError？

Question

我正在开发我的第一个iCloud应用程序.工作一段时间后,由于"UIDocumentStateSavingError",应用程序无法再访问UIManagedDocument.有没有办法真正找出发生了什么错误？

这是我创建UIManagedDocument的代码:

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    iCloudURL = [[NSFileManager defaultManager] URLForUbiquityContainerIdentifier:nil];

    if (iCloudURL == nil) {
        dispatch_async(dispatch_get_main_queue(), ^{
            [self iCloudNotAvailable];
        });
        return;
    }


    iCloudDocumentsURL = [iCloudURL URLByAppendingPathComponent:@"Documents"];
    iCloudCoreDataLogFilesURL = [iCloudURL URLByAppendingPathComponent:@"TransactionLogs"];

    NSURL *url = [iCloudDocumentsURL URLByAppendingPathComponent:@"CloudDatabase"];
    iCloudDatabaseDocument = [[UIManagedDocument alloc] initWithFileURL:url];

    NSMutableDictionary *options = [NSMutableDictionary dictionary];

    NSString *name = [iCloudDatabaseDocument.fileURL lastPathComponent];
    [options setObject:name forKey:NSPersistentStoreUbiquitousContentNameKey];
    [options setObject:iCloudCoreDataLogFilesURL forKey:NSPersistentStoreUbiquitousContentURLKey];

    iCloudDatabaseDocument.persistentStoreOptions = options;

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(documentContentsChanged:) name:NSPersistentStoreDidImportUbiquitousContentChangesNotification object:iCloudDatabaseDocument.managedObjectContext.persistentStoreCoordinator];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(documentStateChanged:) name:UIDocumentStateChangedNotification object:iCloudDatabaseDocument];


    if ([[NSFileManager defaultManager] fileExistsAtPath:[iCloudDatabaseDocument.fileURL path]]) {
        // This is true, the document exists.
        if (iCloudDatabaseDocument.documentState == UIDocumentStateClosed) {
            [iCloudDatabaseDocument openWithCompletionHandler:^(BOOL success) {
                if (success) {
                    dispatch_async(dispatch_get_main_queue(), ^{
                        [self documentConnectionIsReady];
                    });
                } else {
                    dispatch_async(dispatch_get_main_queue(), ^{
                        [self connectionError:iCloudConnectionErrorFailedToOpen];
                    });
                }
            }];                    
        } else if (iCloudDatabaseDocument.documentState == UIDocumentStateNormal) {
            ...
        }      
    } else {
        ...               
    }           
});

Document已经存在,因此在文档上调用openWithCompletionHandler :. 这会失败并触发UIDocumentStateChangedNotification,显示文档状态为5:UIDocumentStateClosed和UIDocumentStateSavingError

在此之后,调用完成块.从这里开始的正确方法是什么？有没有办法找出出了什么问题,发生了什么样的错误？

我试图在完成块中重新打开文档,但结果是一样的.

我想我可以通过删除文件并重新创建它来解决问题.但是,一旦应用程序出现在商店中,这显然不是一种选择.我想知道出了什么问题,并给用户一个合适的方法来处理问题.

我已经在这里检查了处理UIDocumentStateSavingError的其他问题(其中不是很多)但似乎不适用于此处的问题.

知道如何找出问题所在吗？我不能相信API告诉你"保存期间出了问题,但我不会告诉你什么!"

Answer 1

您可以在完成处理程序中查询documentState.不幸的是,如果你想要确切的错误,获得它的唯一方法是子类化并覆盖handleError:userInteractionPermitted:

也许这样的东西会有所帮助(没有编译器的徒手打字)......

@interface MyManagedDocument : UIManagedDocument
 - (void)handleError:(NSError *)error
         userInteractionPermitted:(BOOL)userInteractionPermitted;
@property (nonatomic, strong) NSError *lastError;
@end

@implementation MyManagedDocument
@synthesize lastError = _lastError;
 - (void)handleError:(NSError *)error
         userInteractionPermitted:(BOOL)userInteractionPermitted
{
    self.lastError = error;
    [super handleError:error
           userInteractionPermitted:userInteractionPermitted];
}
@end

然后在你可以像这样创建它...

iCloudDatabaseDocument = [[UIManagedDocument alloc] initWithFileURL:url];

并在像这样的完成处理程序中使用它...

        [iCloudDatabaseDocument openWithCompletionHandler:^(BOOL success) {
            if (success) {
                dispatch_async(dispatch_get_main_queue(), ^{
                    [self documentConnectionIsReady];
                });
            } else {
                dispatch_async(dispatch_get_main_queue(), ^{
                    [self connectionError:iCloudConnectionErrorFailedToOpen
                                withError:iCloudDatabaseDocument.lastError];
                });
            }
        }];