將文件保存到樹給定的樹未知樹深度

Question

假設我有一個NSURL指向我的NSDocumentationDirectory，但NSURL中有未知數量的子目錄。當寫入URL時，我將不得不檢查路徑中是否存在目錄，如果它們不存在，那麼創建它們，還是隻寫入NSURL？如果前者，我該怎麼做？

這是我到目前爲止所嘗試的，它不工作。我認爲這是因爲路徑上的子目錄不存在。

NSData *imageData; 
if (imageURL) { 
    //imageURL points to an image on the internet. 
    NSLog(@"Path components\n%@",[imageURL pathComponents]); 
    NSFileManager *fileManager = [[NSFileManager alloc] init]; 
    NSArray *urls = [fileManager URLsForDirectory:NSDocumentationDirectory inDomains:NSUserDomainMask]; 
    //Sample of urls[0]: file://localhost/var/mobile/Applications/blahblah/Library/Documentation/ 
    NSURL *cachedURL = urls[0]; //iOS, so this will be the only entry. 
    //Manually add a cache directory name. 
    cachedURL = [cachedURL URLByAppendingPathComponent:@"cache"]; 
    NSArray *passedPathComponents = [imageURL pathComponents]; 
    for (NSString *pathComponent in passedPathComponents) { 
     cachedURL = [cachedURL URLByAppendingPathComponent:pathComponent]; 
     NSLog(@"Added component %@ making URL:\n%@",pathComponent,cachedURL); 
    } 
    // Check if image data is cached. 
    // If cached, load data from cache. 
    imageData = [[NSData alloc] initWithContentsOfURL:cachedURL]; 
    if (imageData) { 
     //Cached image data found 
     NSLog(@"Found image data from URL %@",cachedURL); 
    } else { 
     // Did not find the image in cache. Retrieve it and store it. 
     // Else (not cached), load data from passed imageURL. 
     //  Update cache with new data. 
     imageData = [[NSData alloc] initWithContentsOfURL:imageURL]; 
     if (imageData) { 
     // Write the imageData to cache 
     [imageData writeToURL:cachedURL atomically:YES]; //This is the line I'm asking about 
     } 
    } 
    NSLog(@"Value of urls is %@",urls[0]); 
} 

我不感興趣，緩存API的，我可以挖掘到。這個問題的目的是瞭解如何正確使用NSFileManager。

編輯：我想也許我需要使用createDirectoryAtURL：withIntermediateDirectories：attributes：error：在路徑中排除最後一個組件。

Answer 1

我把它用createDirectoryAtURL工作：...如下：

for (NSString *pathComponent in passedPathComponents) { 
    if ([pathComponent isEqualToString:lastComponent]) { 
     //Now we're looking at the file name. Ensure the directory exists. What we have so far is the directory. 
     if ([fileManager createDirectoryAtURL:cachedURL withIntermediateDirectories:YES attributes:nil error:NULL]) { 
      //NSLog(@"Directory was created or already exists"); 
     } else { 
      NSLog(@"Error creating directory %@",[cachedURL description]); 
     }; 
    } 
    cachedURL = [cachedURL URLByAppendingPathComponent:pathComponent]; 
    }