的iOS ALAssetsLibrary和NSFileHandle讀取文件內容

Question

我想用資產defaultRepresentation網址似乎總是返回0x0讀取一個資產庫文件中的內容的iOS

NSFileHandle fileHandleForReadingFromUrl ......

我將繼續尋找同時尋求解決方案。

編輯：

貌似從Anomie答案可能是什麼，我想：

NSUInteger length = [representation getBytes:bytes fromOffset:0 length:[representation size] error:&error];

Answer 1

對於你可能希望通過一個循環來複製出塊讀取X字節的文件，否則您可能會耗盡設備上的內存。

NSUInteger chunkSize = 100 * 1024; 
uint8_t *buffer = malloc(chunkSize * sizeof(uint8_t)); 

ALAssetRepresentation *rep = [myasset defaultRepresentation]; 
NSUInteger length = [rep size]; 

NSFileHandle *file = [[NSFileHandle fileHandleForWritingAtPath: tempFile] retain]; 

if(file == nil) { 
    [[NSFileManager defaultManager] createFileAtPath:tempFile contents:nil attributes:nil]; 
    file = [[NSFileHandle fileHandleForWritingAtPath:tempFile] retain]; 
} 

NSUInteger offset = 0; 
do { 
    NSUInteger bytesCopied = [rep getBytes:buffer fromOffset:offset length:chunkSize error:nil]; 
    offset += bytesCopied; 
    NSData *data = [[NSData alloc] initWithBytes:buffer length:bytesCopied]; 
    [file writeData:data]; 
    [data release]; 
    } while (offset < length); 

[file closeFile]; 
[file release]; 
free(buffer); 
buffer = NULL;