以多種方式訪問​​變量

Question

還是有點新，我遇到了一些問題，希望有人能幫忙。我試圖從我的服務器加載一個JSON字符串到iOS6的collectionview中 我可以使用從viewDidLoad方法調用的fetchedData方法來引入數據，該部分工作正常。在fetchedData方法中，我分解出JSON數據並將它放在NSDictionaries和NSArrays中，並將正確的數據轉儲到日誌中以查看它。

問題是，當我嘗試使用我的代碼中的任何其他信息的任何信息，如獲取任何hte數組中的元素數量作爲計數器來填充collectionview。

這可能是我累了，但我似乎無法繞過這部分。許多主要變量的聲明在fetchedData方法中，我認爲自從在那裏聲明它可能是我在其他地方看不到它們的原因，所以我將變量的聲明移到了接口部分，並希望這會使變量GLOBAL和fetchedData方法繼續正常工作，但沒有其他地方。

當我在單元格定義區域中放置中斷時，可以在調試器窗口中看到變量爲空。

我不確定代碼中的哪些部分可能需要查看，請通知我，我可以發佈它們，但也許有人可以舉例說明如何使用多種方法訪問數組和字典項目。

爲了避免混淆，並暴露我的代碼大雜燴在這一點上無論如何這裏是.m文件或​​至少是大部分它請不要撕裂強硬的編碼風格我一直在嘗試任何我能想到的並且自己撕毀了它，並且很晚了。

#import "ICBCollectionViewController.h" 
#import "ICBCollectionViewCell.h" 
#import "ICBDetailViewController.h" 

@interface ICBCollectionViewController() { 

NSDictionary* json; 
NSDictionary* title; 
NSDictionary* shortDescrip; 
NSDictionary* longDescrip; 
NSDictionary* price; 
NSDictionary* path; 
NSDictionary* sKU; 
NSDictionary* audiotrack; 
NSDictionary* audiotracksize; 



NSArray* titles; 
NSArray* shortDescription; 
NSArray* longDescription; 
NSArray* prices; 
// NSArray* paths; 
NSArray* SKUs; 
NSArray* audiotracks; 
NSArray* audiotracksizes; 
} 
@end 
/* 
@interface NSDictionary(JSONCategories) 
+(NSDictionary*)dictionaryWithContentsOfJSONURLString:(NSString*)urlAddress; 
-(NSData*)toJSON; 
@end 

@implementation NSDictionary(JSONCategories) 
+(NSDictionary*)dictionaryWithContentsOfJSONURLString:(NSString*)urlAddress 
{ 
NSData* data = [NSData dataWithContentsOfURL: [NSURL URLWithString: urlAddress] ]; 
__autoreleasing NSError* error = nil; 
id result = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error]; 
if (error != nil) return nil; 
return result; 
} 

-(NSData*)toJSON 
{ 
NSError* error = nil; 
id result = [NSJSONSerialization dataWithJSONObject:self options:kNilOptions error:&error]; 
if (error != nil) return nil; 
return result; 
} 
@end 
*/ 
@implementation ICBCollectionViewController 
@synthesize paths; 

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil 
{ 
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; 
if (self) { 
    // Custom initialization 
} 
return self; 
} 

- (void)viewDidLoad 
{ 
[super viewDidLoad]; 
dispatch_async(kBgQueue, ^{ 
     NSData* data = [NSData dataWithContentsOfURL: imobURL]; 
     [self performSelectorOnMainThread:@selector(fetchedData:) withObject:data waitUntilDone:YES]; 
}); 

// Do any additional setup after loading the view. 
} 

- (void)fetchedData:(NSData *)responseData { 
NSError* error; 
//parse out the json data 
json = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error]; 

titles = [json objectForKey:@"title"]; //2 
shortDescription = [json objectForKey:@"shortD"]; 
longDescription = [json objectForKey:@"longD"]; 
prices = [json objectForKey:@"price"]; 
self.paths = [json objectForKey:@"path"]; 
SKUs = [json objectForKey:@"SKU"]; 
audiotracks = [json objectForKey:@"audiotrack"]; 
audiotracksizes = [json objectForKey:@"audiotracksize"]; 

NSLog(@"paths: %@", paths); //3 
// NSLog(@"shortDescrip: %@", shortDescription); 

NSInteger t=7; 
    // 1) Get the latest loan 
    title = [titles objectAtIndex:t]; 
    shortDescrip = [shortDescription objectAtIndex:t]; 
    longDescrip = [longDescription objectAtIndex:t]; 
    price = [prices objectAtIndex:t]; 
    path = [paths objectAtIndex:t]; 
    sKU = [SKUs objectAtIndex:t]; 
    audiotrack = [audiotracks objectAtIndex:t]; 
    audiotracksize = [audiotracksizes objectAtIndex:t]; 

    //NSLog(title.count text); 
    //NSLog(title.allValues); 

    // 2) Get the data 
    NSString* Title = [title objectForKey:@"title"]; 
    NSString* ShortDescrip = [shortDescrip objectForKey:@"shortD"]; 
    NSString* LongDescrip = [longDescrip objectForKey:@"longD"]; 
    NSNumber* Price = [price objectForKey:@"price"]; 
    NSString* Path = [path objectForKey:@"path"]; 
    NSString* SKU = [sKU objectForKey:@"SKU"]; 
    NSString* AudioTrack = [audiotrack objectForKey:@"audiotrack"]; 
    NSNumber* AudioTrackSize = [audiotracksize objectForKey:@"audiotracksize"]; 





    /*************************HERE THE DATA EXISTS*******************************/ 
    /******** Path = "XYXYXYXYXYXY" for example ********************************/ 

    // 3) Set the label appropriately 
    NSLog([NSString stringWithFormat:@"Here is some data: Title: %@ Path %@ SKU: %@ Price: %@ Track %@ Size %@",Title, Path, SKU, Price, LongDescrip, AudioTrackSize]); 

} 







- (void)didReceiveMemoryWarning 
{ 
[super didReceiveMemoryWarning]; 
// Dispose of any resources that can be recreated. 
} 

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender { 
//DetailSegue 

if ([segue.identifier isEqualToString:@"DetailSegue"]) { 
    ICBCollectionViewCell *cell = (ICBCollectionViewCell *)sender; 
    NSIndexPath *indexPath = [self.collectionView indexPathForCell:cell]; 
    ICBDetailViewController *dvc = (ICBDetailViewController *)[segue destinationViewController]; 
    dvc.img = [UIImage imageNamed:@"MusicPlayerGraphic.png"]; 

} 
} 

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{ 
NSLog(@"paths qty = %d",[paths count]); 
return 20; 
} 

// The cell that is returned must be retrieved from a call to -dequeueReusableCellWithReuseIdentifier:forIndexPath: 
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{ 
static NSString *identifier=@"Cell"; 
ICBCollectionViewCell *cell = (ICBCollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath]; 

// paths = [json objectForKey:@"path"]; 
NSDictionary* path = [paths objectAtIndex:indexPath.row]; 
NSString* Path = [path objectForKey:@"path"]; 
// NSString* Path = [paths objectAtIndex:indexPath.row]; 
NSLog(@"%d",indexPath.row); 



    /***********************HERE IT DOES NOT**************************/ 
    /******** Path = "" **********************************************/ 

NSLog(@"xxx"); 
NSLog(path); 
NSLog(paths); 
NSLog(Path); 
NSLog(@"ZZZ"); 



Path=@"deepsleep"; 
NSLog(@"xxx"); 
NSLog(Path); 
NSLog(@"ZZZ"); 





// paths = [json objectForKey:@"path"]; 

// NSString* Path = [path objectForKey:@"path"]; 

NSString *imagefile = [NSString stringWithFormat:@"https://imobilize.s3.amazonaws.com/glennharrold/data/%@/mid.png", Path]; 
NSLog(imagefile); 
NSURL *url1=[NSURL URLWithString:imagefile]; 
dispatch_async(kBgQueue, ^{ 
    NSData *data1 = [NSData dataWithContentsOfURL:url1]; 
    cell.imageView.image =[[UIImage alloc]initWithData:data1]; 
}); 
return cell; 
} 


@end 

Answer 1

試着打破JSON數據並將其排序在appDelegate中。如果你聲明公共變量有@property (nonatomic, strong) NSDictionary *myDict等，那麼你可以通過輸入你的appDelegate並使用下面的代碼訪問這些變量：

AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate]; 
NSDictionary *newDict = appDelegate.myDict; 

否則，您可以將信息存儲在一個singleton，或根視圖控制器。關鍵是將你的變量存儲在一個不會被釋放的類中。大多數情況下，爲此目的使用viewController是一個糟糕的主意 - 它們有一種被遠離的趨勢，這會釋放內存並擺脫變量。谷歌「模型視圖控制器」的更多信息。

Answer 2

我發現它的主要問題是ViewDidLoad方法，我使用後臺活動從我的服務器獲取JSON數據，並且該進程正在運行前臺也在處理中，並且由於代碼的其餘部分是基於後臺進程完成時返回的值，實際上該數據爲空，因此基於該單個部分的所有數據也都爲空，並且看起來好像不可用。一旦我在前臺運行該進程，所有變量都開始具有值。

感謝這個