iOS NSKeyedArchiver unarchive返回空數組

Question

我遇到了NSKeyedArchiver的一個問題，它已經困擾了我很長一段時間，似乎無法查明錯誤。

我有一個可變數組，由類「設備」的對象組成。 在我的appDelegate我能保證設備的mutableArray，我有以下三個功能：

- (void) loadDataFromDisk { 
    self.devices = [NSKeyedUnarchiver unarchiveObjectWithFile: self.docPath]; 
    NSLog(@"Unarchiving"); 
} 

- (void) saveDataToDisk { 
    NSLog(@"Archiving"); 
    [NSKeyedArchiver archiveRootObject: self.devices toFile: self.docPath]; 
} 

- (BOOL) createDataPath { 
    if (docPath == nil) { 
     NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES); 
     NSString *docsDir = [paths objectAtIndex:0]; 
     self.docPath = [docsDir stringByAppendingPathComponent: @"devices.dat"]; 
     NSLog(@"Creating path"); 
    } 

    NSLog(@"Checking path"); 

    NSError *error; 
    BOOL success = [[NSFileManager defaultManager] createDirectoryAtPath: docPath withIntermediateDirectories: YES attributes: nil error:&error]; 
    if (!success) { 
     NSLog(@"Error creating data path: %@", [error localizedDescription]); 
    } 
    return success; 
} 

我一直在解檔過程中得到一個空mutableArray。我正在使用ARC，並不確定這與它有什麼關係。

Answer 1

因此，顯然，我不知道的是，您必須首先將您的根對象（本例中爲數組）保存到NSMutableDictionnary。

NSMutableDictionary *rootObject; 
rootObject = [NSMutableDictionary dictionary]; 

[rootObject setValue: self.devices forKey: @"devices"]; 

然後用NSKeyedArchiver保存rootObject。奇怪的是，在任何教程中都沒有看到。

因此，您最終得到以下用於加載和保存數據到NSKeyedArchiver的函數。

- (void) loadArrayFromArchiver { 
    NSMutableDictionary *rootObject = [NSKeyedUnarchiver unarchiveObjectWithFile: [self getDataPath]]; 

    if ([rootObject valueForKey: @"devices"]) { 
     self.devices = [rootObject valueForKey: @"devices"]; 
    } 

    NSLog(@"Unarchiving"); 
} 

- (void) saveArrayToArchiver { 
    NSLog(@"Archiving"); 

    NSMutableDictionary *rootObject = [NSMutableDictionary dictionary]; 

    [rootObject setValue: self.devices forKey: @"devices"]; 

    [NSKeyedArchiver archiveRootObject: rootObject toFile: [self getDataPath]]; 
} 

- (NSString *) getDataPath { 
    self.path = @"~/data"; 
    path = [path stringByExpandingTildeInPath]; 
    NSLog(@"Creating path"); 
}