objective-c - 为什么这个 UIImage 从不更新，即使它引用的文件发生变化？

Question

所以，我在一个 View 中创建一个 UIImage(Cocos2d 游戏的屏幕截图)，如下所示:

    [UIImagePNGRepresentation(screenshot) writeToFile:savePath options:NSDataWritingAtomic error:&error];

稍后，在另一个屏幕上，我在 Cocos2d 菜单中显示所有屏幕截图，如下所示:

-(void) showGardens{

    CCMenu* menu = [[CCMenu alloc] initWithItems:nil vaList:nil];
    menu_items = [NSMutableArray arrayWithCapacity:gardens.count];
    for(Garden* garden in gardens){
        NSLog(@"Making menu item for garden %@", garden.name);
        NSString *loadPath = [NSHomeDirectory() stringByAppendingPathComponent:garden.screen_shot_name];
        CCMenuItem* save_button;
        NSFileManager*  fileManager = [NSFileManager defaultManager];
        if([fileManager fileExistsAtPath:loadPath]){
            save_button = [CCMenuItemImage itemFromNormalImage:loadPath 
                                                             selectedImage:loadPath target:self selector: @selector(loadGarden:)];
        }else{
            save_button = [CCMenuItemImage itemFromNormalImage:@"default_screenshot.png" 
                                                             selectedImage:loadPath target:self selector: @selector(loadGarden:)];
        }


        [save_button autorelease];
        CCLabelTTF *label = [CCLabelTTF labelWithString:garden.name fontName:@"Marker Felt" fontSize:100];

        // position the label on the center of the screen
        label.position =  ccp(300,555);
        ccColor3B color = {0,0,0};
        [label setColor: color]; 
        [save_button addChild: label];      
        save_button.scale = 0.35;
        [menu_items addObject: save_button];

    }
    //make sure its not just overwriting one child.    
    for(CCMenuItem* menu_item in menu_items){
        [menu addChild: menu_item];
        [menu_items retain];
    }
    [menu alignItemsHorizontallyWithPadding:80.0];
    menu.position = ccp(700,500);
    [self addChild: menu];

}

但是，如果屏幕截图稍后被替换，它不会在此 View 中更新，即使据我所知此 View 每次加载时都会调用 [self showGardens] new。如果我完全退出应用程序(强制退出，或其他)然后再次打开它，屏幕截图是正确的。

这是某种内存问题吗？还是应用程序在运行时以某种方式缓存了所有图像，并且仅在完成时才重新加载？

图像存储在如下位置:

/var/mobile/Applications/77DE5CC9-93DE-4346-A8AE-89F38036F718/Documents/Sample Garden17.png

Answer 1

因为 cocos2d 在加载纹理时会缓存纹理。在重新加载文件之前，您需要从缓存中删除纹理。

[[CCTextureCache sharedTextureCache] removeTextureForKey:loadPath];
save_button = [CCMenuItemImage itemFromNormalImage:loadPath 
                                     selectedImage:loadPath 
                                            target:self 
                                          selector:@selector(loadGarden:)];