Question

我无法使用同步调用缓存NSURLConnection响应。我在一个类中初始化缓存，然后在另一个类中使用它。注意缓存内存容量如何初始化为100KB，然后神奇地重置为零。

- (id)init {
    if (self = [super init]) {
         // Creates a custom URL cache that uses both memory and disk.
         NSURLCache *sharedCache = 
         [[NSURLCache alloc] initWithMemoryCapacity:kMemoryCacheSize * 1000000 
         diskCapacity:kDiskCacheSize * 1000000 
         diskPath:diskPath];
         [NSURLCache setSharedURLCache:sharedCache];

        NSLog(@"Cache memory capacity = %d bytes", [[NSURLCache sharedURLCache] memoryCapacity]);
        NSLog(@"Cache disk capacity = %d bytes", [[NSURLCache sharedURLCache] diskCapacity]);

        //[sharedCache release];
    }
    return self;
}
// NSLOG OUTPUT:
// [6842:20b] Cache memory capacity = 100000 bytes
// [6842:20b] Cache disk capacity = 20000000 bytes

在另一堂课......

NSLog(@"Cache memory capacity = %d bytes", [[NSURLCache sharedURLCache] memoryCapacity]);
NSLog(@"Cache disk capacity = %d bytes", [[NSURLCache sharedURLCache] diskCapacity]);
NSLog(@"Cache Memory Usage = %d bytes", [[NSURLCache sharedURLCache] currentMemoryUsage]);
NSLog(@"Cache Disc Usage = %d bytes", [[NSURLCache sharedURLCache] currentDiskUsage]);
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:objectURL cachePolicy:NSURLRequestReturnCacheDataElseLoad timeoutInterval:20];
data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
NSLog(@"Image Request finished. Error = %@",[error localizedDescription]);
NSLog(@"Cache size after = %d bytes", [[NSURLCache sharedURLCache] currentMemoryUsage]);
// NSLog Output:
// Cache memory capacity = 0 bytes
// Cache Disc Usage = 0 bytes
// Cache Memory Usage = 0 bytes
// Cache disk capacity = 20000000 bytes
// Image Request finished. Error = (null)
// Cache size after = 0 bytes

Answer 1

我在使用网页浏览的应用中遇到了这个问题。出于某种原因，当webviews初始化时，它们将缓存归零，不确定原因。在像这样的应用程序中，我使用NSURLCache子类忽略对setMemoryCapacity的调用：如果它们为零。

类似的东西：

-(void)setMemoryCapacity:(NSUInteger)memCap
{
    if (memCap == 0)
        return;
   [super setMemoryCapacity:memCap];
}

Answer 2

我会将“％p”和[NSURLCache sharedURLCache]添加到NSLog语句中，以确保共享对象保持不变。然后我会为+ [NSURLCache setSharedURLCache：]和 - [NSURLCache setMemoryCapacity：]添加断点以查看发生了什么。

Answer 3

这里有同样的问题。思想缓存根本不起作用。在没有UIWebView的情况下设置一个小测试项目后，[NSURLCache sharedURLCache] memoryCapacity]返回预期的10000000而不是0。

幸运的是，缓存不会被清除，所有以前缓存的对象都将保留。所以Dougs解决方案就像一个魅力！

BTW：一旦显示Web视图，大小将设置为零。之后将其设置回10000000，显示Web视图不会再将大小设置为零。

NSURLCache内存大小为零

3 个答案: