利用NSURLProtocol實現webView快取
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { [NSURLProtocol registerClass:[MyURLProtocol class]]; return YES; } |
|
-
(void)connection:(NSURLConnection
*)connection didReceiveResponse:(NSURLResponse
*)response
{
[self.client URLProtocol:self
didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed];
}
-
(void)connection:(NSURLConnection
*)connection didReceiveData:(NSData
*)data
{
[ |
+ (BOOL)canInitWithRequest:(NSURLRequest *)request { static NSUInteger requestCount = 0; NSLog(@"Request #%u: URL = %@", requestCount++, request); if ([NSURLProtocol propertyForKey:@"MyURLProtocolHandledKey" inRequest:request]) { return NO; } return YES; } - (void)startLoading { NSMutableURLRequest *newRequest = [self.request mutableCopy]; [NSURLProtocol setProperty:@YES forKey:@"MyURLProtocolHandledKey" inRequest:newRequest]; self.connection = [NSURLConnection connectionWithRequest:newRequest delegate:self]; } |
@property (nonatomic, strong) NSMutableData *mutableData; @property (nonatomic, strong) NSURLResponse *response; |
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response { [self.client URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed]; self.response = response; self.mutableData = [[NSMutableData alloc] init]; } - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { [self.client URLProtocol:self didLoadData:data]; [self.mutableData appendData:data]; } - (void)connectionDidFinishLoading:(NSURLConnection *)connection { [self.client URLProtocolDidFinishLoading:self]; [self saveCachedResponse]; } |
- (void)saveCachedResponse { NSLog(@"saving cached response"); // 1. AppDelegate *delegate = [[UIApplication sharedApplication] delegate]; NSManagedObjectContext *context = delegate.managedObjectContext; // 2. CachedURLResponse *cachedResponse = [NSEntityDescription insertNewObjectForEntityForName:@"CachedURLResponse" inManagedObjectContext:context]; cachedResponse.data = self.mutableData; cachedResponse.url = self.request.URL.absoluteString; cachedResponse.timestamp = [NSDate date]; cachedResponse.mimeType = self.response.MIMEType; cachedResponse.encoding = self.response.textEncodingName; // 3. NSError *error; BOOL const success = [context save:&error]; if (!success) { NSLog(@"Could not cache the response."); } } |
- (CachedURLResponse *)cachedResponseForCurrentRequest { // 1. AppDelegate *delegate = [[UIApplication sharedApplication] delegate]; NSManagedObjectContext *context = delegate.managedObjectContext; // 2. NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"CachedURLResponse" inManagedObjectContext:context]; [fetchRequest setEntity:entity]; // 3. NSPredicate *predicate = [NSPredicate predicateWithFormat:@"url == %@", self.request.URL.absoluteString]; [fetchRequest setPredicate:predicate]; // 4. NSError *error; NSArray *result = [context executeFetchRequest:fetchRequest error:&error]; // 5. if (result && result.count > 0) { return result[0]; } return nil; } |
- (void)startLoading { // 1. CachedURLResponse *cachedResponse = [self cachedResponseForCurrentRequest]; if (cachedResponse) |