需要懶表格圖像加載應用程序的文檔文件夾中的圖像

Question

我有我的圖像到我的iPhone應用程序的文檔目錄。

我把它們加載到表中。但我希望它們加載爲懶表圖像

我已經通過googling出來，但發現圖像從服務器加載的鏈接。

如何從我的文檔目錄加載它們？

我試過這個鏈接，但沒有爲我工作。所以請不要認爲這是重複，因爲它沒有爲我，所以我不得不發佈此問題的其他一些答案

Lazy load images for UITableViewCells from NSDocumentDirectory?

Answer 1

從服務器下載影像的工作解決方案可以輕鬆地工作被修改爲從NSDocumentsDirectory加載。這是一個簡單的實現，你可以創建一個獨立的類或集成到一個現有的類。我沒有包括100％的代碼，只是放在足以顯示加載圖像。 imageLoader.h需要定義一個協議，包括imageLoader:didLoadImage:forKey:以及_delegate和_images的iVars /屬性。

// imageLoader.m 

// assumes that that images are cached in memory in an NSDictionary 
- (UIImage *)imageForKey:(NSString *)key 
{ 
    // check if we already have the image in memory 
    UImage *image = [_images objectForKey:key]; 

    // if we don't have an image: 
    // 1) start a background task to load an image from available sources 
    // 2) return a default image to display while loading 
    if (!image) { 
     // this is the simplest example of background execution 
     // if you need more control use NSOperationQueue or Grand Central Dispatch 
     [self performSelectorInBackground:@selector(loadImageForKey) withObject:key]; 
     image = [self defaultImage]; 
    } 

    return image; 
} 

// attempts to load an image from available sources and notifies the delegate when done 
- (void)loadImageForKey:(NSString *)key 
{ 
    NSAutoReleasePool *pool = [[NSAutoReleasePool alloc] init]; 

    // attempt to load the image from a file 
    UIImage *image = [UIImage imageWithContentsOfFile:[self imagePathForKey]]; 

    // if no image, attempt to load the image from an URL here if desired 

    // if no image, return default or notFound image 
    if (!image) { 
     image = [self notFoundImage]; 
    } 

    if ([_delegate respondsTo:@selector(imageLoader:didLoadImage:ForKey:)]) { 
     // this message will be sent on the same thread as loadImageForKey 
     // you can either modify this to send the message on the main thread 
     // or ensure the delegate does any desired UI changes on the main thread 
     [_delegate imageLoader:self didLoadImage:image forKey:key]; 
    } 

    [pool release]; 
} 

// returns a path to the image in NSDocumentDirectory 
- (NSString)imagePathForKey:(NSString *)key 
{ 
    NSString *path; 
    // your implementation here 
    return path; 
}