objective-c - 应用程序不释放内存，内存使用量每次都会增加一倍

Question

我创建了一个函数，可以帮助在 NSString 数组中查找重复文件(数组包含文件路径)

这是我的功能:

-(NSMutableArray *)compareWithList:(NSMutableArray*)fileCompareList // list of file from which we need to find the duplicates of the target
                          fileData:(NSData*)_fileData // contains target file data bytes
                        fileLength:(UInt32) _fileLenght // contains size of target file
{
    // result list of the (duplcate)files
    NSMutableArray* fileList = [[NSMutableArray alloc]init];

    // flag to check if the path is a folder
    BOOL isDir;

    //stores the size of the file that is being itrated
    UInt32 size = 0;
    //stores the byte data of the file that is being itrated
    NSData *bytes = nil;

    //itrating the files in the list one by one in order find the duplicate
    for (NSString* sPath in fileCompareList) {
        //checking if the file already exists in the result list
        if ([fileList indexOfObject:sPath] == NSNotFound)
        {
            //getting the size of the file
            UInt32 size = [sysHelp getSizeOfFile:sPath];
            //if the size matches of the target file and the itrated file then go inside
            if(size == _fileLenght)
            {
                //get the bytes of the file being itrated
                bytes = [[NSData alloc] initWithContentsOfFile:sPath];

                //if the bytes matches then add the itrated file into the result list
                if([bytes isEqualToData:_fileData])
                {
                    [fileList addObject:sPath];
                }
                //remove the itrated file data from the array
                bytes = nil;
            }
        }

    }

    return fileList;
}

这里的问题是，由于函数的内存使用量变得很高，如下面的屏幕截图所示:

之前

之后

一段时间后

注意；我正在使用ARC

我如何调用该函数？这是:

NSMutableArray* allFilesOfSystem =[[NSMutableArray alloc] init];
allFilesOfSystem = self AllFilesOfDesktopAndSubDirectores];

NSMutableArray* FinalResultArray = [[NSMutableArray alloc] init];

for (int i = 0; i < [allFilesOfSystem count]; i++) {

        NSString* filePath = [allFilesOfSystem objectAtIndex:i];

        //file to byte array
        NSData *bytes = [[NSData alloc] initWithContentsOfFile:filePath];

        //file size
        UInt32 size = [sysHelp getSizeOfFile:filePath];

        [FinalResultArray addObjectsFromArray:[self compareWithList:allFilesOfSystem fileData:bytes fileLength:size]]

}

Answer 1

请将您的所有语句移至 @ autoreleasepool 中，并告诉我是否有帮助。下面是代码

-(NSMutableArray *)compareWithList:(NSMutableArray*)fileCompareList // list of file from which we need to find the duplicates of the target
                          fileData:(NSData*)_fileData // contains target file data bytes
                        fileLength:(UInt32) _fileLenght // contains size of target file
{
  // result list of the (duplcate)files
  NSMutableArray* fileList = [[NSMutableArray alloc] init];
  
  @autoreleasepool {
    // flag to check if the path is a folder
    BOOL isDir;
    
    //stores the size of the file that is being itrated
    UInt32 size = 0;
    //stores the byte data of the file that is being itrated
    NSData *bytes = nil;
    
    //itrating the files in the list one by one in order find the duplicate
    for (NSString* sPath in fileCompareList) {
      //checking if the file already exists in the result list
      if ([fileList indexOfObject:sPath] == NSNotFound)
      {
        //getting the size of the file
        UInt32 size = [sysHelp getSizeOfFile:sPath];
        //if the size matches of the target file and the itrated file then go inside
        if(size == _fileLenght)
        {
          //get the bytes of the file being itrated
          bytes = [[NSData alloc] initWithContentsOfFile:sPath];
          
          //if the bytes matches then add the itrated file into the result list
          if([bytes isEqualToData:_fileData])
          {
            [fileList addObject:sPath];
          }
          //remove the itrated file data from the array
          bytes = nil;
        }
      }
      
    }
  }
  return fileList;
}

<小时/>

编辑:说明

有两种方法可以放弃对象的所有权。一种是释放，另一种是自动释放。如果您对一个对象调用release，并且该对象的保留计数变为立即释放，但如果您自动释放一个对象，则一旦自动释放池被释放/耗尽，即延迟释放，就会发送释放消息。让我们举个例子。

- (void)testMemoryInARC1 {
  NSData *data = [[NSData alloc] initWithContentsOfFile:@"myfile.mp3"]; // reatin count is 1
  //used this data an after few statements
  //statement 1
  // ..
  
  
  //at the end of data varibale scope in this case it's the end of method
  //ARC will insert the release call
  // [data rlease]; //wchich releases the memory
}


- (void)testMemoryInARC2 {
  NSData *data = [NSData dataWithContentsOfFile:@"myfile.mp3"]; // this method returns the autorelase object
  //used this data an after few statements
  //statement 1
  // ..
  
  
  //at the end of data varibale scope in this case it's the end of method
  //ARC will NOT insert the release call since that was autoreleased object
  //hence no release call
}

那么问题来了，它什么时候发布？
ARS 说:“好问题，当自动释放池结束(已释放)时，它将被释放”。

自动释放池何时结束？
ARC 说，“只需检查您在哪里创建了自动释放池，如果您还没有创建它，那么 main.m 文件中有一个主自动释放池”

这意味着当 main 方法完成时，所有自动释放对象都会被释放，这对我程序结束有何帮助？
ARC 说:“又是一个好问题!Cocoa 库在整个开发过程中都使用了自动释放池，如果您没有使用过它，那么先生，这是您的问题而不是我的问题。”

About Memory Management