iPhone内存泄漏和malloc？

Question

好吧，我终于可以在实际的 iPad 上测试我的 iPad 应用程序了...

我的应用程序所做的一件事是在 ScrollView 中显示大(2mb)图像。这导致 iPad 收到内存警告。我在仪器中运行该应用程序来检查是否有泄漏。

当我加载图像时，检测到泄漏，并且我在分配中看到以下内容:

所有分配:83.9 MBMalloc 48.55 MB:48.55 MBMalloc 34.63 MB:34.63 MB

我想了解的是如何明显地堵塞泄漏，以及为什么 2MB 图像会导致 20 倍大小的 malloc

我对 obj-c 编程非常陌生，所以我确信这是一件显而易见的事情，但我就是无法弄清楚。这是代码:

@interface ChartsViewController : UIViewController <UIScrollViewDelegate, UIPickerViewDelegate, UIPickerViewDataSource> {
    IBOutlet UIScrollView *scrollView;
    UIImageView *imageView;
    NSString *chart;
    NSString *chartFile;
    UIPickerView *picker;
    NSDictionary *chartsDictionary;
    NSArray *chartTypes;
    NSArray *charts;
    IBOutlet UILabel *chartNameLabel;
    IBOutlet UIActivityIndicatorView *activityIndicator;



}

@property (nonatomic, retain) UIScrollView *scrollView;
@property (nonatomic, retain) UIImageView *imageView;
@property (nonatomic, retain) NSString *chart;
@property (nonatomic, retain) NSString *chartFile;
@property (nonatomic, retain) IBOutlet UIPickerView *picker;
@property (nonatomic, retain) NSDictionary *chartsDictionary;
@property (nonatomic, retain) NSArray *chartTypes;
@property (nonatomic, retain) NSArray *charts;
@property (nonatomic, retain) IBOutlet UILabel *chartNameLabel;
@property (nonatomic, retain) IBOutlet UIActivityIndicatorView *activityIndicator;


-(IBAction) chartSelected;
- (void)alertView:(UIAlertView *)actionSheet 

////////////////////////////////

-(IBAction) chartSelected {
    [imageView removeFromSuperview];
    imageView = nil;
    chartNameLabel.text = @"";

    NSInteger chartTypeRow = [picker selectedRowInComponent:kChartTypeComponent];
    NSInteger chartRow= [picker selectedRowInComponent:kChartComponent];
    chart = [self.charts objectAtIndex:chartRow];
    chartFile = [chart stringByReplacingOccurrencesOfString:@" " withString:@"_"];


    NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
                                                         NSUserDomainMask, YES);


    NSString *docsPath = [paths objectAtIndex:0];
    NSString *tempString = [[NSString alloc]initWithFormat:@"%@/%@.jpg",docsPath,chartFile];




    NSData *temp = [NSData dataWithContentsOfFile:tempString];

    if (temp != NULL){

        temp = nil;
        [imageView removeFromSuperview];
        imageView = nil;

        UIImageView *tempImage = [[UIImageView alloc]initWithImage:[UIImage imageWithContentsOfFile: tempString]];
        [tempString release];
        self.imageView = tempImage;


        scrollView.contentSize = CGSizeMake(imageView.frame.size.width , imageView.frame.size.height);
        scrollView.maximumZoomScale = 4.0;
        scrollView.minimumZoomScale = .05;
        scrollView.clipsToBounds = YES;
        scrollView.delegate = self;
        scrollView.zoomScale = .3;

        [scrollView addSubview:imageView];
        [tempImage release];
        imageView = nil;
        chartNameLabel.text = chart;

    }

    else {

        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Download Chart" 
                                                       message:@"It appears that you have not yet downloaded this chart. Press OK to download this chart to your iPad. Depending on your internet connection, the download could take several minutes." 
                                                      delegate:self 
                                             cancelButtonTitle:@"OK" 
                                             otherButtonTitles:@"Cancel", nil];
        [alert show];
        [alert release];

    }

    }

- (void)dealloc {

    [imageView release];
    [scrollView release];
    [chartsDictionary release];
    [picker release];
    [chartTypes release];
    [charts release];
    [super dealloc];
}

Answer 1

你说你有一个 2MB 的图像。但这意味着 2MB JPG，对吗？

那么像素大小是多少 - 因为当您将图像加载到内存中时，它必须被解压缩。这意味着内存中的大小将是水平分辨率 * 垂直分辨率 * 8 * 4(Alpha channel )字节。

这就是为什么您每次加载镜像时都会看到分配了 20-30MB，无论保留问题如何(这仅意味着分配的每个 30MB 都不会被释放)。