iphone标签栏应用程序视图生命周期问题

Question

这可能是一个愚蠢的问题，并带有简单的答案。我是iOS开发新手，这让我很难过。

我有一个基本的标签栏应用程序。该应用程序在启动时加载初始选项卡，并且它是一个tableview控制器。这个tableview的数据是由一个datacontroller提供的，它通过从互联网获取的数据创建一个数组。当我第一次启动应用程序时，没有任何东西显示在桌面视图中，它是空的。但是，如果我选择不同的选项卡，然后返回到该选项卡，数据现在就会显示在桌面视图中，就像它应该那样。我如何获得第一次显示的数据？这显然是在那里。我相信这可能与数据加载导致问题的位置/时间有关，任何洞察力都会很好。

这台DataController类的应用程序委托：

// Create Locations data controller. 
LocationDataController *controller = [[LocationDataController alloc] init]; 
self.locationDataController = controller; 
[controller release]; 
locationsViewController.locationDataController = locationDataController; 

这里的DataController类代码：

@implementation LocationDataController 
@synthesize fetchConnection = mFetchConnection; 
@synthesize locations, tempLocations; 



-(id)initData { 
    if (self = [super init]) { 
     [self createData]; 
    } 
    return self; 
} 

-(id)init { 
    [self fetchData]; 
    return self; 
} 


-(unsigned)countOfList { 
    return [locations count]; 
} 


-(Location *)objectInListAtIndex:(unsigned)theIndex { 
    return [locations objectAtIndex:theIndex]; 
} 


-(void)dealloc { 
    [locations release]; 

    if (mFetchConnection != nil) { 
     [mFetchConnection cancel]; 
     [mFetchConnection release]; 
    } 

    if (mFetchConnectionBuffer != nil) 
     [mFetchConnectionBuffer release]; 

    [super dealloc]; 
} 


#pragma mark - 
#pragma mark Fetching/Sending Data 
#pragma mark 

- (void)fetchData { 
    if (mFetchConnection == nil) { 
     if (mFetchConnectionBuffer != nil) 
      [mFetchConnection release]; 

     mFetchConnectionBuffer = [[NSMutableData alloc] init]; 

     NSURLRequest *request = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:kFetchURLPath]]; 
     self.fetchConnection = [[[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES] autorelease]; 
     [request release]; 
    } 
} 




#pragma mark - 
#pragma mark NSURLConnection Delegate 
#pragma mark 

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)inData { 
    if (connection == mFetchConnection) { 
     [mFetchConnectionBuffer appendData:inData]; 
    } 
} 




- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)connectionError { 
    if (connection == mFetchConnection) { 
     self.fetchConnection = nil; 
     [mFetchConnectionBuffer release]; 
     mFetchConnectionBuffer = nil; 
    } 
} 



- (void)connectionDidFinishLoading:(NSURLConnection *)connection { 

    tempLocations = [[NSMutableArray alloc] init]; 

    if (connection == mFetchConnection) { 
     NSString *str = [[NSString alloc] initWithData:mFetchConnectionBuffer encoding:NSUTF8StringEncoding]; 
     SBJSON *parser = [[SBJSON alloc] init]; 
     id result = [parser objectWithString:str error:nil]; 
     if (result != nil && [result isKindOfClass:[NSArray class]]) 
      [tempLocations setArray:result]; 
     [str release]; 
     [mFetchConnectionBuffer release]; 
     mFetchConnectionBuffer = nil; 
     self.fetchConnection = nil; 

     [self initData]; 

    } 
} 


-(void)createData { 

    // Cycle through array to implement locations. 
    Location *location; 
    NSMutableArray *array = [[NSMutableArray alloc] init]; 

    // create arry of locations. 
    for (int i=0; i<[tempLocations count];i++) { 

     location = [[Location alloc] init]; 
     location.name = [[tempLocations objectAtIndex:i] objectForKey:@"name"]; 
     location.address = [[tempLocations objectAtIndex:i] objectForKey:@"address"]; 
     location.city = [[tempLocations objectAtIndex:i] objectForKey:@"city"]; 
     location.state = [[tempLocations objectAtIndex:i] objectForKey:@"state"]; 
     location.zip = [[tempLocations objectAtIndex:i] objectForKey:@"zip"]; 

     [array addObject:location]; 
     [location release]; 

    } 

    self.locations = array; 
    [array release]; 
    [tempLocations release]; 

} 

Answer 1

假设你已经正确实施的TableView委托方法，我建议你打电话的tableView。在创建数据之后重新加载数据以查看是否有效。