GCD ve KVO problemleri

Question

Uygulamam, albümün albüm listesini ve belirli albümdeki tüm fotoğrafları almak istiyor.

Uygulamada fotoğrafları iphone'un bir albümünde numaralandırıyorum. Belli bir albümden çok sayıda fotoğraf olabileceğinden, performans düşünüldüğünde GCD: dispatch_async kullanıyorum. Ancak, KVO tarafından çağrılan tablo görüntüleme hücresi güncellemeleri her zaman kilitlenir. KVO veya GCD'nin yanlış kullanılıp kullanılmadığı hakkında hiçbir fikrim yok.

Şimdi alternatif olarak performSelectorInBackground kullanıyorum: dispatch_async öğesinin değiştirilmesi. Artık uygulama çökmedi, ancak uygulamanın performansı düşük: Hücrenin başlığı yalnızca dokunduğunuzda veya çok sayıda fotoğraf olduğunda tablo görünümünü kaydırdığınızda gösterilir. Başka bir deyişle, ana iş parçacığı engellenmelidir.

Eklenen kod ve temel kod AlbumListViewController.m içinde.

Herhangi biri kontrol etmeme yardım edebilir mi?

Bilmek istediklerim: 1 neden dispatch_async 2 kullanılıyorsa uygulamanın çökmesi neden oluyor? Birçok fotoğrafta performansı nasıl artırabilirim.

Teşekkürler.

 
// 
// RootViewController.h 
// AlbumDemo 


#import 

@interface RootViewController : UITableViewController { 
    NSMutableArray *_listArray; 
} 

@property (nonatomic, retain) NSMutableArray *listArray; 

@end 


// RootViewController.m 


#import "RootViewController.h" 
#import 
#import "AlbumListViewController.h" 
NSString *thumnail = @"thumnail"; 
NSString *albumName = @"albumName"; 
NSString *albumNum = @"albumNum"; 
NSString *albumGroup = @"albumGroup"; 
@implementation RootViewController 
@synthesize listArray = _listArray; 

#pragma - 
#pragma Function 
- (void)setUp 
{ 
    _listArray = [[NSMutableArray alloc] initWithCapacity:1]; 
    self.title = @"Albums"; 
} 
- (void)fetchAlbumList 
{ 
    ALAssetsLibrary *assetLib = [[[ALAssetsLibrary alloc] init] autorelease]; 
    ALAssetsFilter *fileter = [ALAssetsFilter allPhotos]; 
    [assetLib enumerateGroupsWithTypes:ALAssetsGroupAll 
          usingBlock:^(ALAssetsGroup *group, BOOL *stop) 
    { 
     if (group) 
     { 
      [group setAssetsFilter:fileter]; 
      NSString *_groupName = [group valueForProperty:ALAssetsGroupPropertyName]; 
      NSNumber *_groupNum = [NSNumber numberWithInteger:[group numberOfAssets]]; 
      UIImage *_groupImage = [UIImage imageWithCGImage:[group posterImage]]; 

      NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:_groupName,albumName,_groupNum,albumNum,_groupImage,thumnail,group,albumGroup, nil]; 

      [_listArray addObject:dic]; 
      [self.tableView reloadData]; 

     } 
     else 
     { 
      NSLog(@"_listArray :%@",_listArray); 
     } 

    } 
          failureBlock:^(NSError *error) 
    { 
     NSLog(@"Error: %@", error);; 
    } 
    ]; 

} 
#pragma - 
#pragma ViewController lift cycle 
- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    [self setUp]; 
    [self fetchAlbumList]; 

} 

- (void)viewWillAppear:(BOOL)animated 
{ 
    [super viewWillAppear:animated]; 
} 

- (void)viewDidAppear:(BOOL)animated 
{ 
    [super viewDidAppear:animated]; 
} 

- (void)viewWillDisappear:(BOOL)animated 
{ 
    [super viewWillDisappear:animated]; 
} 

- (void)viewDidDisappear:(BOOL)animated 
{ 
    [super viewDidDisappear:animated]; 
} 

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    return 50; 
} 
// Customize the number of sections in the table view. 
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView 
{ 
    return 1; 
} 

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{ 
    return [_listArray count]; 
} 

// Customize the appearance of table view cells. 
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    static NSString *CellIdentifier = @"Cell"; 
    UILabel *nameLab = nil; 
    UILabel *numLab = nil; 
    UIImageView *thumnailImage = nil; 

    UIFont *font = [UIFont boldSystemFontOfSize:18]; 

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; 
    if (cell == nil) { 
     cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; 
     cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator; 

     thumnailImage = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0,50, 50)]; 
     thumnailImage.tag = 100; 
     [cell.contentView addSubview:thumnailImage]; 
     [thumnailImage release]; 


     nameLab = [[UILabel alloc] initWithFrame:CGRectMake(60, 10, 100, 30)]; 
     nameLab.tag = 200; 
     nameLab.backgroundColor = [UIColor clearColor]; 
     nameLab.font = font; 
     [cell.contentView addSubview:nameLab]; 
     [nameLab release]; 

     numLab = [[UILabel alloc] initWithFrame:CGRectMake(200, 10, 50, 30)]; 
     numLab.tag = 300; 
     numLab.backgroundColor = [UIColor clearColor]; 
     numLab.textColor = [UIColor grayColor]; 
     numLab.font = font; 
     [cell.contentView addSubview:numLab]; 
     [numLab release]; 
    } 
    else 
    { 
     thumnailImage = (UIImageView *)[cell.contentView viewWithTag:100]; 
     nameLab = (UILabel *)[cell.contentView viewWithTag:200]; 
     numLab = (UILabel *)[cell.contentView viewWithTag:300]; 
    } 

    NSDictionary *dic = [self.listArray objectAtIndex:indexPath.row]; 

    thumnailImage.image = (UIImage *)[dic valueForKey:thumnail]; 

    NSString *title = [dic valueForKey:albumName]; 
    CGSize titleSize = [title sizeWithFont:font]; 
    CGRect rect = nameLab.frame; 
    rect.size = titleSize; 
    nameLab.frame = rect; 
    nameLab.text = title; 

    rect = numLab.frame; 
    rect.origin.x = 60 + nameLab.frame.size.width + 10; 
    numLab.frame = rect; 

    numLab.text = [NSString stringWithFormat:@"(%d)",[[dic valueForKey:albumNum] intValue]]; 


    // Configure the cell. 
    return cell; 
} 

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    NSDictionary *dic = [self.listArray objectAtIndex:indexPath.row]; 

    AlbumListViewController *viewController = [[AlbumListViewController alloc] initWithAssetGroup:[dic valueForKey:albumGroup]]; 
    [self.navigationController pushViewController:viewController animated:YES]; 
    [viewController release]; 
    [tableView deselectRowAtIndexPath:indexPath animated:YES]; 
} 

- (void)didReceiveMemoryWarning 
{ 
    // Releases the view if it doesn't have a superview. 
    [super didReceiveMemoryWarning]; 

    // Relinquish ownership any cached data, images, etc that aren't in use. 
} 

- (void)viewDidUnload 
{ 
    [super viewDidUnload]; 

    // Relinquish ownership of anything that can be recreated in viewDidLoad or on demand. 
    // For example: self.myOutlet = nil; 
} 

- (void)dealloc 
{ 
    My_Release (_listArray); 
    [super dealloc]; 
} 

@end 


// AlbumListViewController.h 
// AlbumDemo 

#import 
#import 

@interface AlbumListViewController : UITableViewController { 
    NSMutableArray *_marr; 
    ALAssetsGroup *_assetsGroup; 
} 

@property (nonatomic, retain) NSMutableArray *list; 
@property (nonatomic, retain) ALAssetsGroup *assetsGroup; 

- (id)initWithAssetGroup:(ALAssetsGroup *)group; 
@end 

// AlbumListViewController.m 
// AlbumDemo 

#import "AlbumListViewController.h" 

@interface PhotoObj : NSObject { 
    NSString *_name; 
    UIImage *_thumbnail; 
    UIImage *_fullImage; 
} 

@property (nonatomic, copy ) NSString *name; 
@property (nonatomic, retain) UIImage *thumbnail; 
@property (nonatomic, retain) UIImage *fullImage; 
@end 

@implementation PhotoObj 
@synthesize name = _name; 
@synthesize thumbnail = _thumbnail,fullImage = _fullImage; 
- (void)dealloc 
{ 
    My_Release(_thumbnail); 
    My_Release(_fullImage); 
    My_Release(_name); 
    [super dealloc]; 
} 
@end 

@interface AlbumListViewController() 

- (NSMutableArray*)list; 
- (NSUInteger)countOfList; 
- (id)objectInListAtIndex:(NSUInteger)idx; 
- (void)insertObject:(id)anObject inListAtIndex:(NSUInteger)idx; 
- (id)objectInListAtIndex:(NSUInteger)idx; 
- (void)removeObjectFromListAtIndex:(NSUInteger)idx; 
- (void)replaceObjectInListAtIndex:(NSUInteger)idx withObject:(id)anObject; 
- (void)setList:(NSMutableArray *)_arr; 

@end 

@implementation AlbumListViewController 
@synthesize assetsGroup = _assetsGroup; 

- (id)initWithAssetGroup:(ALAssetsGroup *)group 
{ 
    self = [self initWithStyle:UITableViewStylePlain]; 
    if (self) 
    { 
     _marr = [[NSMutableArray alloc] initWithCapacity:1]; 
     self.assetsGroup = group; 
     self.tableView.delegate = self; 
     self.tableView.dataSource = self; 

    } 
    return self; 
} 

- (id)initWithStyle:(UITableViewStyle)style 
{ 
    self = [super initWithStyle:style]; 
    if (self) { 
     // Custom initialization 
    } 
    return self; 
} 

- (void)dealloc 
{ 
    My_Release(_marr); 
    My_Release(_assetsGroup); 
    [self removeObserver:self forKeyPath:@"list"]; 
    [super dealloc]; 
} 

- (void)didReceiveMemoryWarning 
{ 
    // Releases the view if it doesn't have a superview. 
    [super didReceiveMemoryWarning]; 

} 

#pragma mark - View lifecycle 
- (void)parseAssetGroup 
{ 
    [_marr removeAllObjects]; 
    [self.assetsGroup enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) { 
     if (result) 
     { 
      PhotoObj *obj = [[PhotoObj alloc] init]; 
      obj.thumbnail = [UIImage imageWithCGImage:[result thumbnail]]; 
      ALAssetRepresentation *represention = [result defaultRepresentation]; 
      obj.fullImage = [UIImage imageWithCGImage:[represention fullScreenImage]]; 
      obj.name = [[represention url] absoluteString]; 


      [self willChangeValueForKey:@"list"]; 
      [self insertObject:obj inListAtIndex:[_marr count]]; 
      [self didChangeValueForKey:@"list"]; 
      My_Release(obj); 
     } 

    }]; 

} 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    [self addObserver:self forKeyPath:@"list" options:NSKeyValueObservingOptionNew |NSKeyValueObservingOptionOld context:NULL]; 
    /* 
    if performSelectorInBackground, the perofrmance is poor 
    as the title of the cell will be shown in a long time and it now seems the main thread is blocked 
    */ 
    [self performSelectorInBackground:@selector(parseAssetGroup) withObject:nil]; 
    /* 
    using dispatch_async it always crashes 
    as it says the sth is wrong with the tableview update 

    */ 

// dispatch_async(dispatch_get_main_queue(), ^{ 
//  [self parseAssetGroup]; 
// }); 
} 

- (void)viewDidUnload 
{ 
    [super viewDidUnload]; 

} 

#pragma mark - Table view data source 
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    return 50; 
} 
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView 
{ 
    // Return the number of sections. 
    return 1; 
} 

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{ 
    // Return the number of rows in the section. 
    return [_marr count]; 
} 

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    static NSString *CellIdentifier = @"Cell"; 

    UIImageView *thumbNail = nil; 
    UILabel *nameLab = nil; 
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; 
    if (cell == nil) { 
     cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; 
     cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator; 

     thumbNail = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 50, 50)]; 
     thumbNail.tag = 99; 
     [cell.contentView addSubview:thumbNail]; 
     [thumbNail release]; 

     nameLab = [[UILabel alloc] initWithFrame:CGRectMake(60, 10, 240, 40)]; 
     nameLab.numberOfLines = 2; 
     nameLab.font = [UIFont systemFontOfSize:16]; 
     nameLab.tag = 199; 
     [cell.contentView addSubview:nameLab]; 
     [nameLab release]; 
    } 
    else 
    { 
     thumbNail = (UIImageView *)[cell.contentView viewWithTag:99]; 
     nameLab = (UILabel *)[cell.contentView viewWithTag:199]; 
    } 
    // Configure the cell... 
    PhotoObj *obj = [_marr objectAtIndex:indexPath.row]; 
    nameLab.text = obj.name; 
    thumbNail.image = obj.thumbnail; 

    return cell; 
} 
#pragma mark - 
- (NSUInteger)countOfList 
{ 
    return [_marr count]; 
} 
- (NSMutableArray*)list 
{ 
    return _marr; 
} 
- (void)setList:(NSMutableArray *)_arr 
{ 
    if (_marr != _arr) 
    { 
     [_marr release]; 
     _marr = _arr; 
    } 
} 

- (id)objectInListAtIndex:(NSUInteger)idx 
{ 
    return [_marr objectAtIndex:idx]; 
} 

- (void)insertObject:(id)anObject inListAtIndex:(NSUInteger)idx 
{ 
    if ([NSThread isMainThread]) 
    { 
     NSLog(@"insert main thread"); 
    } 
    else 
    { 
     NSLog(@"insert not main thread"); 
    } 
    [_marr insertObject:anObject atIndex:idx]; 
} 


- (void)removeObjectFromListAtIndex:(NSUInteger)idx 
{ 
    [_marr removeObjectAtIndex:idx]; 
} 
- (void)replaceObjectInListAtIndex:(NSUInteger)idx withObject:(id)anObject 
{ 
    [_marr replaceObjectAtIndex:idx withObject:anObject]; 
} 
- (void)observeValueForKeyPath:(NSString *)keyPath 
         ofObject:(id)object 
         change:(NSDictionary *)change 
         context:(void *)context 
{ 
    NSIndexSet *indices = [change objectForKey:NSKeyValueChangeIndexesKey]; 
    if (indices == nil) 
     return; // Nothing to do 

    // Build index paths from index sets 
    NSUInteger indexCount = [indices count]; 
    NSUInteger buffer[indexCount]; 
    [indices getIndexes:buffer maxCount:indexCount inIndexRange:nil]; 

    NSMutableArray *indexPathArray = [NSMutableArray array]; 
    for (int i = 0; i

Answer 1

Bugün aynı sorun koştu:

Aşağıda benim Kod olduğunu. Kısacası, neden UIKit ile ilgili bir tabloyu güncellemeyi, ya da benim durumumda bir arka plan gönderme sırasından bir Textview gibi yapamazsınız. Daha fazla bilgi için aşağıdaki bağlantıyı kontrol edin.

comparison GCD vs. performSelectorInBackground: dispatch_async not in background

Muhtemel bir çözüm takip ediyor: Bunun yerine doğrudan çökmesine neden KVO değişkene Güncelleştirme bloğunun içinde taze verileri atama, sen ana sıranın bunu yapamaz başka bloğu sevk, Güncelleme bloğunuzun içinden. Bunu yapmak için dispatch_async_f işlevini kullanırsanız, verilerinize bir işaretçi bağlam olarak geçirebilirsiniz. Bunun gibi

:

dispatch_async(yourQueue, ^() { 
    NSArray *data; 
    // do stuff to alloc and fill the array 
    // ... 
    dispatch_async(dispatch_get_main_queue(), ^() { 
    myObj.data = data; // the assignment, which triggers the KVO. 
    }); 
}); 

Benim için bu istinat ve veri bırakmadan çalışır. Bu doğruysa, emin değilim.