NSURLCache 内存大小为零
我在使用同步调用缓存 NSURLConnection 响应时遇到问题。我在一个类中初始化缓存,然后在另一个类中使用它。请注意高速缓存容量如何初始化为 100KB,但随后又神奇地重置为零。
- (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
在另一个班级...
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
I am having trouble caching NSURLConnection responses using a synchronous call. I initialize the cache in one class and then use it in another. Notice how the cache memory capacity gets initialized to 100KB but then is magically reset to zero later.
- (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
In another class...
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
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我在带有网络视图的应用程序中遇到了这个问题。由于某种原因,当 webview 初始化时,它们会将缓存归零,不知道为什么。在这样的应用程序中,我使用 NSURLCache 子类,该子类会忽略对 setMemoryCapacity: 的调用(如果它们为零)。
像这样的东西:
I've had this problem in apps with webviews. For some reason when webviews initialize they zero the cache, not sure why. In apps like this I use a NSURLCache subclass that ignore calls to setMemoryCapacity: if they are zero.
something like:
我会将“%p”和 [NSURLCache sharedURLCache] 添加到您的 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:] 添加断点来查看发生了什么。
I would add "%p" and [NSURLCache sharedURLCache] to your NSLog statements to make sure the shared object remains the same. Then I would add breakpoints for +[NSURLCache setSharedURLCache:] and -[NSURLCache setMemoryCapacity:] to see what's going on.
这里也有同样的问题。以为缓存根本不起作用。设置一个没有 UIWebView 的小型测试项目后,[NSURLCache共享URLCache]内存容量]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将保留。所以道格斯的解决方案很有魅力!
顺便说一句:一旦显示网页视图,大小将设置为零。之后将其设置回 10000000,显示 Web 视图不会再次将大小设置为零。
Had the same problem here. Thought caching doesn't work at all. After setting up a small test project without a UIWebView, the [NSURLCache sharedURLCache] memoryCapacity] returns the expected 10000000 instead of 0.
Luckily the cache will not be cleared, all previously cached objects will remain. So Dougs solution works like a charm!
BTW: once a web view is shown the size will be set to zero. Setting it back to 10000000 afterwards, showing a web view will not set the size to zero again.