iOS NSURLConnection (sendAsynchronousRequest :) too much cache

Question

我的应用程序中有几个内存泄漏(不!请参阅更新 1)，它们都归结为异步 URLRequest。下面的代码给了我一个内存泄漏，似乎“数据”从未被释放(下面的代码在逻辑上没有在我的应用程序中使用，因为它是一个完全无用的无限循环，我只是写它来显示内存泄漏。这个使使用的 RAM 在不到一秒内从 5 MB 增加到 20 MB。我的网速确实符合这个 [仅作记录]):

- (void)start{
    NSOperationQueue *oQC = [[NSOperationQueue alloc] init];
    NSLog(@"a");
    [NSURLConnection sendAsynchronousRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.online-image-editor.com//styles/2014/images/example_image.png"]] queue:oQC completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
        NSLog(@"b");
        [self start];
    }];
}

我也试过设置 data = nil，但是，就像假设的那样，不起作用。是否有人知道如何避免内存泄漏以及这是否是 NSURLConnection 的正常行为？

更新 1:

这似乎与内存泄漏无关，而是与缓存问题有关。 (感谢@rdelmar，他看到了问题，但他的解决方案并不奏效)

基于 this post我尝试在它的 .h 文件中创建一个新的“Loader”类:

#import <Foundation/Foundation.h>

@interface Loader : NSObject <NSURLConnectionDelegate, NSURLConnectionDataDelegate>

@property NSMutableData *mData;
@property (nonatomic, copy) void (^returnBlock)(NSData *data, NSError *error);

- (id)initForWhateverWithURLString:(NSString*)urlString andHandler:(void (^)(NSData *data, NSError *error))handler;

@end

这是 .m 文件中的内容:

#import "Loader.h"

@implementation Loader

@synthesize mData;

- (id)initForWhateverWithURLString:(NSString*)urlString andHandler:(void (^)(NSData *data, NSError *error))handler{
    self = [super init];
    if (self) {
        /*NSOperationQueue *oQC = [NSOperationQueue mainQueue];
        [NSURLConnection sendAsynchronousRequest:mUR queue:oQC completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
            [[NSURLCache sharedURLCache] removeCachedResponseForRequest:mUR];
            handler(nil, nil);
         }];*/
        mData = [NSMutableData new];
        self.returnBlock = handler;
        NSMutableURLRequest *mUR = [[NSURLRequest requestWithURL:[NSURL URLWithString:urlString] cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:60] mutableCopy];
        NSURLConnection *URLCon = [[NSURLConnection alloc] initWithRequest:mUR delegate:self];
        [URLCon start];
    }
    return self;
}

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

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
    [mData appendData:data];
    data = nil;
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
    self.returnBlock(mData, nil);
    mData = nil;
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
    self.returnBlock(nil, error);
}

@end

我还实现了:

NSURLCache *sharedCache = [[NSURLCache alloc] initWithMemoryCapacity:0 diskCapacity:0 diskPath:@"nsurlcache"];
[NSURLCache setSharedURLCache:sharedCache];

尽管如此，这些方法都无法帮助减少急剧的 RAM 使用量!

Answer 1

我不认为你看到的是泄漏。我认为内存不断增加，因为正在缓存数据。如果您更改请求的缓存协议(protocol)，问题就会消失(您将获得默认行为，NSURLRequestUseProtocolCachePolicy，通过使用 requestWithURL:)

- (void)viewDidLoad {
    [super viewDidLoad];
    self.req = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.online-image-editor.com//styles/2014/images/example_image.png"] cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:10];
    [self start];
}

- (void)start{
    NSOperationQueue *oQC = [NSOperationQueue mainQueue]; // this queue is where the completion block runs, so you should use mainQueue if you want to do any UI updating
    NSLog(@"a");
    [NSURLConnection sendAsynchronousRequest:self.req queue:oQC completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
        NSLog(@"b");
        [self start];
    }];
}

编辑后:

在进一步查看之后，我不确定为什么 sendAsynchronousRequest: 会导致内存使用量随时间增加。我使用 NSURLSession(无论如何我们现在应该使用它)进行了测试，这似乎没有导致内存增加。

- (void)viewDidLoad {
    [super viewDidLoad];
    NSString *urlString = @"http://www.online-image-editor.com//styles/2014/images/example_image.png";
    self.req = [NSURLRequest requestWithURL:[NSURL URLWithString:urlString] cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:10];
    [self start];
}

- (void)start{
    NSLog(@"a");
    NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[NSOperationQueue mainQueue]];
    NSURLSessionDataTask *task = [session dataTaskWithRequest:self.req completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        self.counter ++;
        NSLog(@"counter is: %ld", self.counter);
        [self start];
    }];
    [task resume];
}