將對象添加到Parse.com類時出現異常

Question

我在創建和發送記錄到Parse時遇到以下異常，我想知道是否有人可以闡明它，或者如何尋找解決方案..

2014-04-23 22:38:19.397 DreamCatching[10731:303] Can't use nil for keys or values on PFObject. Use NSNull for values.
2014-04-23 22:38:19.399 DreamCatching[10731:303] (
    0   CoreFoundation                      0x00007fff8933a25c __exceptionPreprocess + 172
    1   libobjc.A.dylib                     0x00007fff89827e75 objc_exception_throw + 43
    2   CoreFoundation                      0x00007fff8933a10c +[NSException raise:format:] + 204
    3   ParseOSX                            0x00000001000cc9ac -[PFObject setObject:forKey:] + 69
    4   DreamCatching                       0x000000010000681f -[DreamViewController endPlaces:] + 975
    5   AppKit                              0x00007fff8dfbd260 -[NSApplication sendAction:to:from:] + 327
    6   AppKit                              0x00007fff8dfbd0de -[NSControl sendAction:to:] + 86
    7   AppKit                              0x00007fff8e009c4d -[NSCell _sendActionFrom:] + 128
    8   AppKit                              0x00007fff8e023655 -[NSCell trackMouse:inRect:ofView:untilMouseUp:] + 2316
    9   AppKit                              0x00007fff8e022a27 -[NSButtonCell trackMouse:inRect:ofView:untilMouseUp:] + 487
    10  AppKit                              0x00007fff8e02213d -[NSControl mouseDown:] + 706
    11  AppKit                              0x00007fff8dfa3a58 -[NSWindow sendEvent:] + 11296
    12  AppKit                              0x00007fff8df425d4 -[NSApplication sendEvent:] + 2021
    13  AppKit                              0x00007fff8dd92a19 -[NSApplication run] + 646
    14  AppKit                              0x00007fff8dd7d7a3 NSApplicationMain + 940
    15  DreamCatching                       0x000000010001a862 main + 34
    16  libdyld.dylib                       0x00007fff886a45fd start + 1
    17  ???                                 0x0000000000000003 0x0 + 3
)

我發送的記錄看起來像這樣（在崩潰之前記錄）：

2014-04-23 22:38:19.397 DreamCatching[10731:303] endPlaces: newJoin: <DDPlaceJoin:new:(null)> {
    ACL = "<PFACL: 0x6100002574f0>";
    mainKey = 070213681717;
    mainName = "About Time";
    parseUser = "<PFUser:BJdxGyXnkn>";
    placeKey = 042314094048;
    placeName = London;
}

Parse對象中沒有其他用戶元素。 這也只是偶爾發生，盡管經常發生。

我的代碼如下：

- (IBAction)endPlaces:(id)sender {
    NSLog(@"%s", __FUNCTION__);
    //selectedPlaces should be in its final state.
    //use it to rebuild the placesJoin class

    [self endSheet:self.sheet returnCode:result];

    //rebuild Places Join array and save it. The replacement info is in selectedPlaces

    //1. empty the current join array for this dream

    [self clearPlaceJoins];

    [PFQuery clearAllCachedResults];

    // 2. Build new join table based on selectedPlaces

    //NSLog(@"There are some Places noted in this dream");
    NSLog(@"endPlaces: selectedPlaces is %@", selectedPlaces);
    NSLog(@"endPlaces: selectedPlaces Count is %lu", (unsigned long)selectedPlaces.count);

    for (int i=0; i < selectedPlaces.count; i++) {

        PFObject *newJoin = [PFObject objectWithClassName:@"DDPlaceJoin"];
        NSString *tempDreamKey = [selectedPlaces[i] valueForKey:@"mainKey"];
        NSString *tempPlaceKey = [selectedPlaces[i] valueForKey:@"placeKey"];
        NSString *tempDreamName = [selectedPlaces[i] valueForKey:@"mainName"];
        NSString *tempPlaceName = [selectedPlaces[i] valueForKey:@"placeName"];

        [newJoin setObject:tempDreamKey forKey:@"mainKey"];
        [newJoin setObject:tempPlaceKey forKey:@"placeKey"];
        [newJoin setObject:tempDreamName forKey:@"mainName"];
        [newJoin setObject:tempPlaceName forKey:@"placeName"];
        [newJoin setObject:[PFUser currentUser] forKey:@"parseUser"];

        query.cachePolicy = kPFCachePolicyNetworkElseCache;

        //Set ACL permissions for added security
        PFACL *joinACL = [PFACL ACLWithUser:[PFUser currentUser]];
        [newJoin setACL:joinACL];

        NSLog(@"endPlaces: newJoin: %@", newJoin);

        [newJoin saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
            if (error) {
                // Revert state on save error.
                NSLog(@"Error saving a placejoin");
            }
        }];

    }

}

謝謝你的幫助。

Answer 1

錯誤消息非常具有描述性， newJoin上設置的對象newJoin是nil。 也許它是[PFUser currentUser] 。

你可以像每次調用setObject一樣處理它...

[newJoin setObject:tempDreamKey ?: [NSNull null] forKey:@"mainKey"];

Answer 2

崩潰發生在對setObject:forKey:一次調用中，這意味着你的NSLog在崩潰之后。 您可能看到最后一條記錄有效，而不是引起問題的記錄。

嘗試在第一個setObject:forKey:之前放置一個斷點或NSLog setObject:forKey:並確保所有的temp*值都是非零的。 如果它們是零並且它們永遠不應該是，那么你可能想弄清楚原因。 否則，您應該確保在將它們添加到PFObject之前監視這些值並將它們更改為[NSNull null] 。