Question

我希望有人可以帮助我。我很难找到一个简单问题的答案。顺便说一句，这是我在使用c和c＃多年后的第一个主要的obj-c项目，所以请随时指出我失败的事情。

我有一个iPhone应用程序，旨在将照片专辑加载到UIScrollView中。它还具有随机图像功能，该功能使用相同的过程但仅显示单个图像。它的工作原理如下：

读取外部XML Feed（存储在ruby-on-rails网站上），其中包含解析后随机网址的路径。
使用NSURLConnection将URL内容下载到NSData。
创建并推送ScrollView
Subclassed UIView分配一个UIImageView，使用NSData分配一个UIImage，在UIImageView中使用UIimage，最后将imageview添加到UIView。
然后父视图将UIView添加到UIScrollView，然后将其推到前面。

当需要下一个随机图像时，再次发生此过程。除了将几个UIView添加到UIScrollView之外，它在显示整个图像专辑时也使用相同的过程。

问题是，尽管在适当的地方使用了release和delloc，但活动工具指示在请求下一个图像时，NSURLConnection和UIImage使用的内存不会从内存中释放。通过在iPhone上构建应用程序进一步证明了这一点。连续请求多个图像会导致应用程序崩溃，可能是因为内存消耗。

以下是一些代码，因为合同协议我无法发布整个项目。

URLDownload类（使用DataDownload）

@implementation URLDownload
    -(NSData *)GetURL:(NSURL *)strURL
{

NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    DataDownload *request = [DataDownload alloc];
request.strURL = strURL;
[request init];

NSRunLoop *runLoop = [NSRunLoop currentRunLoop];
while (request.isLoading && [runLoop runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]]);

[pool release];

return [request urlData];
[request release];

}

DataDownload类

@implementation DataDownload
@synthesize urlData, connection, strURL, isLoading;

- (id)init
{
if(self = [super init])
{

    self.isLoading = YES;

    NSURLRequest *dataRequest = [NSURLRequest requestWithURL:self.strURL
                                             cachePolicy:NSURLRequestReloadIgnoringCacheData
                                         timeoutInterval:60];

    /* establish the connection */  
    self.connection = [[NSURLConnection alloc]
                 initWithRequest:dataRequest
                 delegate:self
    ];

    if (connection == nil) {
        self.urlData = nil; 
    } else {
        self.urlData = [NSMutableData data];   
    }

}

return self;

}

- (void)dealloc {
[connection cancel];
[connection release];
[urlData release];
[strURL release];
[super dealloc];
}

- (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse {
return nil;
}

 -(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse*)response
 {
[urlData setLength:0];
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
 }

 -(void)connection:(NSURLConnection *)connection didReceiveData:(NSData*)incrementalData
{
[self.urlData appendData:incrementalData];
}

-(void)connectionDidFinishLoading:(NSURLConnection*)connection
{
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
self.isLoading = NO;
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
   self.isLoading = NO;
}

@end

ImageView子类

@implementation ImageView

@synthesize strURL, imvImageView, image, currentlyRotated, imgOptionsView, startDate;

- (id)initWithFrame:(CGRect)frame {
if (self = [super initWithFrame:frame]) {       

    self.imvImageView = [UIImageView alloc];    

    if (self.strURL != nil){
        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
        NSData *datImageData = [NSData dataWithContentsOfURL: [NSURL URLWithString:self.strURL]];
        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];

        self.image = [UIImage imageWithData: datImageData];


        CGSize imgSize = image.size;
        CGFloat fltWidth = imgSize.width;
        CGFloat fltHeight = imgSize.height;

        [imvImageView initWithImage:image];

        // If landscape rotate image
        if (fltWidth > fltHeight){
            imvImageView.frame = CGRectMake(-80.0, 80.0, 480.0, 320.0);

            CGAffineTransform rotate = CGAffineTransformMakeRotation(-1.57079633);
            [imvImageView setTransform:rotate];

            self.currentlyRotated = YES;
        }else{
            imvImageView.frame = CGRectMake(0.0, 0.0, 320.0, 480.0);

            self.currentlyRotated = NO;
        }

        [image release];
    }else{
        self.image = [UIImage alloc];
        [imvImageView initWithImage:image];
        [image release];
    }

    [self addSubview:imvImageView];

}

[imvImageView release];

return self;
}

- (void)drawRect:(CGRect)rect {
// Drawing code
}


- (void)dealloc {
[strURL release];
[imvImageView release];
[image release];
[imgOptionsView release];
[startDate release];
[super dealloc];
}

图像显示方式的示例代码

- (void)displayImage:(NSString *)strURL {
NSString *strFullURL = @"http://www.marklatham.co.uk";
strFullURL = [strFullURL stringByAppendingString:strURL];

self.scroller = [[UIScrollView alloc] initWithFrame:CGRectMake(0.0, 0.0, 320.0, 480.0)];
[scroller setContentSize:CGSizeMake(320.0, 540.0)];
[self.view addSubview:scroller];

CGRect rect = CGRectMake(0.0, 0.0, 320.0, 480.0);   
self.imageView = [ImageView alloc];
imageView.strURL = strFullURL;
[imageView initWithFrame:rect];
[scroller addSubview:imageView];

[scroller release];
[imageView release];

}

以下图片显示所有分配以说明正在发生的事情。图1显示启动时的alloc，在加载第一个图像后显示2个，在第二个图像后显示3个。

http://www.gretanova.com/misc/iphone/1.png＆amp; 2.png＆amp; 3.png

谢谢大家，利

Answer 1

有几件事情发生了。例如，在URLDownload类中，永远不会达到对[request release]的调用，因为它放在return语句之后

return [request urlData];
[request release];

iPhone应用程序中的内存分配，发布和NSURLConnection

1 个答案: