從解析下載圖像

Question

我試圖從解析後端下載圖像。它通過創建一個PFQuery，設置Parse類的名稱，可選地設置日期（將在最終版本中的ofc）並查找對象，在UITableView的背景中顯示「今天的圖像」。但是，它給了我一個錯誤。

// Create a query and set it up to find todays pic 
NSLocale *currentLocale = [NSLocale currentLocale]; 
PFQuery *todayQuery = [PFUser query]; 
todayQuery = [PFQuery queryWithClassName:@"Today"]; 
[todayQuery findObjectsInBackgroundWithBlock:^(NSArray *result, NSError *error) { 
    // Download the image 
    NSData *imageData; 
    for (PFObject *object in result) {imageData = [object objectForKey:@"todaysPic"];} 

    // Use the image 
    UIImage *todaysPicture = [UIImage imageWithData:imageData]; 
    UIImage *finalTodaysPicture = [[UIImage alloc] init]; 
    finalTodaysPicture = [self blur:todaysPicture]; 
    self.tableView.backgroundColor = [UIColor colorWithPatternImage:finalTodaysPicture]; 
}]; 

// Convert to JPEG with 50% quality 
NSData* data = UIImageJPEGRepresentation([UIImage imageNamed:@"star.jpg"], 0.5f); 
PFFile *imageFile = [PFFile fileWithName:@"Image.jpg" data:data]; 

這裏是我的解析行：

的Xcode告訴我這一點：

2014-10-09 19:05:55.496 iStory[1082:4130995] -[PFFile length]: unrecognized selector sent to instance 0x7fd18bc311f0 

和：

(lldb) bt 
* thread #1: tid = 0x3f0cf1, 0x000000010c4d6b8a libobjc.A.dylib`objc_exception_throw, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1 
frame #0: 0x000000010c4d6b8a libobjc.A.dylib`objc_exception_throw 
frame #1: 0x000000010c84450d CoreFoundation`-[NSObject(NSObject) doesNotRecognizeSelector:] + 205 
frame #2: 0x000000010c79c7fc CoreFoundation`___forwarding___ + 988 
frame #3: 0x000000010c79c398 CoreFoundation`__forwarding_prep_0___ + 120 
frame #4: 0x000000010d077559 UIKit`_UIImageRefFromData + 57 
frame #5: 0x000000010cedc55f UIKit`-[UIImage(UIImagePrivate) _initWithData:preserveScale:cache:] + 110 
frame #6: 0x000000010ced89d1 UIKit`+[UIImage imageWithData:] + 50 
* frame #7: 0x000000010ab937cf iStory`__37-[HomeViewController viewWillAppear:]_block_invoke(.block_descriptor=0x00007f94495a3c40, result=0x00007f9449552b80, error=0x0000000000000000) + 655 at HomeViewController.m:70 
frame #8: 0x000000010abe0ac7 iStory`__49-[BFTask(.block_descriptor=<unavailable>, task=<unavailable>) thenCallBackOnMainThreadAsync:]_block_invoke + 251 at BFTask+Private.m:59 
frame #9: 0x000000010abf91a8 iStory`__41-[BFTask continueWithExecutor:withBlock:]_block_invoke_2(.block_descriptor=0x00007f94495a50d0) + 30 at BFTask.m:287 
frame #10: 0x000000010e651cc6 libdispatch.dylib`_dispatch_call_block_and_release + 12 
frame #11: 0x000000010e66f7f4 libdispatch.dylib`_dispatch_client_callout + 8 
frame #12: 0x000000010e658991 libdispatch.dylib`_dispatch_main_queue_callback_4CF + 956 
frame #13: 0x000000010c7a5569 CoreFoundation`__CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9 
frame #14: 0x000000010c76846b CoreFoundation`__CFRunLoopRun + 2043 
frame #15: 0x000000010c767a06 CoreFoundation`CFRunLoopRunSpecific + 470 
frame #16: 0x000000010ff409f0 GraphicsServices`GSEventRunModal + 161 
frame #17: 0x000000010cea6550 UIKit`UIApplicationMain + 1282 
frame #18: 0x000000010ab928a3 iStory`main(argc=1, argv=0x00007fff55077370) + 115 at main.m:14 
frame #19: 0x000000010e6a4145 libdyld.dylib`start + 1 
(lldb) 

非常感謝幫助！

謝謝！

真誠， 埃裏克

Answer 1

我固定它是這樣的：

-(void)viewWillAppear:(BOOL)animated { 
[super viewWillAppear:YES]; 
// Create a query and set it up to find todays pic 
NSLocale *currentLocale = [NSLocale currentLocale]; 
PFQuery *todayQuery = [PFUser query]; 
todayQuery = [PFQuery queryWithClassName:@"Today"]; 
[todayQuery findObjectsInBackgroundWithBlock:^(NSArray *result, NSError *error) { 
    // Download the image 
    NSData *imageData; 
    PFObject *imageObject; 
    for (imageObject in result) { 
     PFFile *imageFile = (PFFile *)[imageObject objectForKey:@"todaysPic"]; 
     [imageFile getDataInBackgroundWithBlock:^(NSData *resultData, NSError *error) { 
      if (!error) { 
       // Create and set the image 
       UIImage *todaysImage = [UIImage imageWithData:resultData]; 
       UIImage *blurredTodaysImage = [self blur:todaysImage]; 
       self.tableView.backgroundColor = [UIColor colorWithPatternImage:blurredTodaysImage ]; 
      } else { 
       // Just set a default picture 
      } 
     }]; 
    } 
}];