在完成块内完成操作后没有得到结果

Question

这是我的解析器类，在解析了包含对象数组的json url之后，此类完美工作。

@interface parseOperation : NSOperation 
@property (nonatomic, copy) void (^errorHandler)(NSError *error); 

@property (nonatomic, strong, readonly) NSMutableArray *appRecordList; 

- (id)initWithData:(NSData *)data; 
@end 

#import "parseOperation.h" 

@interface parseOperation() <NSURLConnectionDataDelegate> 
{ 
NSMutableArray *array; 
NSMutableData *mdata; 
NSURLConnection *conn; 

// NSMutableArray *arrone; 

} 
@property (nonatomic, strong) NSMutableArray *appRecordList; 
@property (nonatomic, strong) NSData *dataToParse; 
@property (nonatomic, strong) NSMutableArray *workingArray; 
@property (nonatomic, strong) Jobs *workingEntry; 
@property (nonatomic, strong) NSMutableString *workingPropertyString; 
@property (nonatomic, strong) NSArray *elementsToParse; 
@property (nonatomic, readwrite) BOOL storingCharacterData; 
@end 

@implementation parseOperation 
- (id)initWithData:(NSData *)data 
{ 
self = [super init]; 
if (self != nil) 
{ 
    _dataToParse = data; 

} 
return self; 
} 
- (void)handleError:(NSError *)error 
{ 
    NSString *errorMessage = [error localizedDescription]; 
    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Cannot Show Top Paid Apps.........." 
                  message:errorMessage 
                delegate:nil 
              cancelButtonTitle:@"OK" 
              otherButtonTitles:nil]; 
[alertView show]; 
} 

- (void)main 
{ 
    //self.workingArray = [NSMutableArray array]; 
    self.workingPropertyString = [NSMutableString string]; 
    self.workingArray=[[NSMutableArray alloc]init]; 

NSDictionary *allData=[NSJSONSerialization JSONObjectWithData:_dataToParse options:0 error:nil]; 

for (NSDictionary *dict in allData) 
{ 

    self.workingEntry =[[Jobs alloc]init]; 
    self.workingEntry.title=[dict objectForKey:@"title"]; 

    [self.workingArray addObject:self.workingEntry]; 


    self.workingEntry=nil; 

} 
    if (![self isCancelled]) 
{ 

    self.appRecordList = [NSMutableArray arrayWithArray:self.workingArray]; 

    NSLog(@"self.appRecordList======== %@", self.appRecordList); 
    NSLog(@"parse complete......"); 

} 

    // self.workingArray = nil; 
self.workingPropertyString = nil; 
self.dataToParse = nil; 
} 


@end 

我在这里有分析后的结果，self.appRecordList阵列正显示出正确的结果，但我的问题是，当IAM试图访问从具有空值的appdelegate数组。

@interface AppDelegate : UIResponder <UIApplicationDelegate> 
{ 
UINavigationController *nav; 

} 

@property (strong, nonatomic) UIWindow *window; 

@property (nonatomic, strong) NSMutableArray *entries; 

@end 



#import "AppDelegate.h" 
static NSString *const TopPaidAppsFeed =@"http:url"; 


@interface AppDelegate() 
@property (nonatomic, strong) NSOperationQueue *queue; 
@property (nonatomic, strong) NSOperationQueue *queue1; 
@property (nonatomic, strong) NSURLConnection *appListFeedConnection; 
@property (nonatomic, strong) NSMutableData *appListData; 

@end 



@implementation AppDelegate 

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{ 
NSURLRequest *urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:TopPaidAppsFeed]]; 
self.appListFeedConnection = [[NSURLConnection alloc] initWithRequest:urlRequest delegate:self]; 

NSAssert(self.appListFeedConnection != nil, @"Failure to create URL connection."); 

[UIApplication sharedApplication].networkActivityIndicatorVisible = YES; 


return YES; 
} 


- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response 
{ 
self.appListData = [NSMutableData data]; 
} 

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data 
{ 
[self.appListData appendData:data]; // append incoming data 
} 


- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error 
{ 
    [UIApplication sharedApplication].networkActivityIndicatorVisible = NO; 

    if ([error code] == kCFURLErrorNotConnectedToInternet) 
    { 

     NSDictionary *userInfo = [NSDictionary dictionaryWithObject:@"No Connection Error" 
                 forKey:NSLocalizedDescriptionKey]; 
    NSError *noConnectionError = [NSError errorWithDomain:NSCocoaErrorDomain 
                code:kCFURLErrorNotConnectedToInternet 
               userInfo:userInfo]; 
    [self handleError:noConnectionError]; 
} 
else 
{ 
    // otherwise handle the error generically 
    [self handleError:error]; 
} 

self.appListFeedConnection = nil; // release our connection 
} 


- (void)connectionDidFinishLoading:(NSURLConnection *)connection 
{ 
self.appListFeedConnection = nil; // release our connection 

[UIApplication sharedApplication].networkActivityIndicatorVisible = NO; 

// create the queue to run our ParseOperation 
self.queue = [[NSOperationQueue alloc] init]; 

// create an ParseOperation (NSOperation subclass) to parse the RSS feed data 
// so that the UI is not blocked 
parseOperation *parser = [[parseOperation alloc] initWithData:self.appListData]; 

parser.errorHandler = ^(NSError *parseError) { 
    dispatch_async(dispatch_get_main_queue(), ^{ 
     [self handleError:parseError]; 
    }); 
}; 

// Referencing parser from within its completionBlock would create a retain 
// cycle. 
__weak parseOperation *weakParser = parser; 

parser.completionBlock = ^(void) { 
    if (weakParser.appRecordList) { 
     // The completion block may execute on any thread. Because operations 
     // involving the UI are about to be performed, make sure they execute 
     // on the main thread. 
     dispatch_async(dispatch_get_main_queue(), ^{ 
      NSLog(@"completionBlock"); 

      NSLog(@"weakParser.appRecordList====%@", weakParser.appRecordList);//null 

      self.entries=[[NSMutableArray alloc]init]; 
      self.entries = weakParser.appRecordList; 
          NSLog(@"self.entries====%@", self.entries);//null 
      NSLog(@"weakParser.appRecordList====%@", weakParser.appRecordList); 

     }); 
    } 

    // we are finished with the queue and our ParseOperation 
    self.queue = nil; 
}; 

[self.queue addOperation:parser]; // this will start the "ParseOperation" 

// ownership of appListData has been transferred to the parse operation 
// and should no longer be referenced in this thread 
self.appListData = nil; 
} 

@end 

这个完成块里面的weakParser.appRecordList显示为null，请大家帮忙。这里是我的输出画面

Answer 1

你可以尝试删除，在完成块dispatch_async(dispatch_get_main_queue()......，只是做

if (weakParser.appRecordList) { 
     self.entries=[[NSMutableArray alloc]init]; 
     self.entries = weakParser.appRecordList; 
} 

看看它的工作