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littleV/Cache.m

Created September 28, 2018 18:34
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Cache.m
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Cache.m
#import "Cache.h"
#import <WebKit/Webkit.h>
static NSInteger expireCacheMilliSeconds = 300000; // expire content cached longer than 5 minutes
@interface CacheOperation : NSOperation <UIWebViewDelegate, WKNavigationDelegate>
{
BOOL executing;
BOOL finished;
}
@property NSInteger loadingCount;
@property NSURL *httpsHost;
@property UIWebView *uiwebviewCache;
@property WKWebView *wkwebviewCache;
@property NSString* htmlToLoad;
@property NSMutableArray *cacheIds;
@property (nonnull) void (^sendCacheIds)(NSError *, NSArray *);
- (instancetype)initWithContentsToCache: (NSArray *)contents forHost: (NSString *) hostURL withComletionHandler:(void (^)(NSError *, NSArray *))completionBlock;
@end
@implementation CacheOperation
- (instancetype)initWithContentsToCache:(NSArray *)contents forHost:(NSString *)hostURL withComletionHandler:(void (^)(NSError *, NSArray *))completionBlock
{
if (self = [super init]) {
executing = NO;
finished = NO;
self.sendCacheIds = completionBlock;
if (contents == nil || contents.count == 0) {
[self finishAndChangeState];
return self;
}
if (hostURL == nil || [hostURL isEqualToString:@""]) {
[self finishAndChangeState];
return self;
}
long long milliseconds = (long long)([[NSDate date] timeIntervalSince1970] * 1000.0);
NSMutableString *htmlToLoad = [[NSMutableString alloc] init];
[htmlToLoad appendString:@"<head>"];
NSString *scriptString = [NSString stringWithFormat:@"<script>var currentTime = %lld;var toBeDeleted = [];for(i = 0; i< localStorage.length; i ++){if(localStorage.key(i).startsWith('LocalCache_')) {createdTime = localStorage.key(i).split('_')[2];if (( currentTime - createdTime) > %ld){toBeDeleted.push(localStorage.key(i));}}}for ( i = 0; i< toBeDeleted.length; i ++) {localStorage.removeItem(toBeDeleted[i]);}</script>", milliseconds, (long) expireCacheMilliSeconds];
[htmlToLoad appendString:scriptString];
self.cacheIds = [[NSMutableArray alloc] init];
for (NSString *content in contents) {
NSString *cacheId = [NSString stringWithFormat:@"LocalCache_%@_%lld", [NSString stringWithFormat:@"%08X", arc4random()], milliseconds];
[self.cacheIds addObject:cacheId];
[htmlToLoad appendString:[NSString stringWithFormat:@"<script>localStorage.setItem(\"%@\",\"%@\");</script>", cacheId, [self escapeHTML:content]]];
}
[htmlToLoad appendString:@"</head>"];
self.htmlToLoad = htmlToLoad;
_uiwebviewCache = [[UIWebView alloc] init];
_uiwebviewCache.frame = CGRectZero;
_uiwebviewCache.delegate = self;
_wkwebviewCache = [[WKWebView alloc] init];
_wkwebviewCache.frame = CGRectZero;
_wkwebviewCache.navigationDelegate = self;
_httpsHost = [NSURL URLWithString:hostURL];
_loadingCount = 2;
}
return self;
}
-(void)start
{
if ([self isCancelled])
{
// Must move the operation to the finished state if it is canceled.
[self willChangeValueForKey:@"isFinished"];
finished = YES;
[self didChangeValueForKey:@"isFinished"];
return;
}
// If the operation is not canceled, begin executing the task.
[self willChangeValueForKey:@"isExecuting"];
[NSThread detachNewThreadSelector:@selector(main) toTarget:self withObject:nil];
executing = YES;
[self didChangeValueForKey:@"isExecuting"];
}
-(void)main
{
@try {
dispatch_async(dispatch_get_main_queue(), ^{
[self.wkwebviewCache removeFromSuperview];
UIWindow *window = [[UIApplication sharedApplication] keyWindow];
[window addSubview:self.wkwebviewCache];
[self.wkwebviewCache loadHTMLString:self.htmlToLoad baseURL:self.httpsHost];
[self.uiwebviewCache loadHTMLString:self.htmlToLoad baseURL:self.httpsHost];
});
}
@catch (NSException *exception) {
NSLog(@"Catch the exception %@",[exception description]);
}
@finally {
NSLog(@"Cache Operation - Main Method - Finally block");
}
}
-(BOOL)isConcurrent
{
return YES; //Default is NO so overriding it to return YES;
}
-(BOOL)isExecuting{
return executing;
}
-(BOOL)isFinished{
return finished;
}
- (void)webViewDidFinishLoad:(UIWebView *)webView
{
self.loadingCount--;
if (self.loadingCount == 0) {
[self finishAndChangeState];
}
}
- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation
{
self.loadingCount--;
if (self.loadingCount == 0) {
[self finishAndChangeState];
}
}
- (void) finishAndChangeState
{
__weak CacheOperation *weakSelf = self;
dispatch_async(dispatch_get_main_queue(), ^{
__strong CacheOperation *strongSelf = weakSelf;
[strongSelf.wkwebviewCache setNavigationDelegate:nil];
[strongSelf.wkwebviewCache setUIDelegate:nil];
[strongSelf.wkwebviewCache removeFromSuperview];
strongSelf.wkwebviewCache = nil;
strongSelf.uiwebviewCache = nil;
if (self.cacheIds != nil && self.cacheIds.count > 0) {
if (strongSelf.sendCacheIds != nil) {
strongSelf.sendCacheIds(nil, self.cacheIds);
}
} else {
if (strongSelf.sendCacheIds != nil) {
strongSelf.sendCacheIds([NSError errorWithDomain:self.httpsHost.absoluteString code:0 userInfo:nil], nil);
}
}
[strongSelf willChangeValueForKey:@"isExecuting"];
strongSelf->executing = NO;
[strongSelf didChangeValueForKey:@"isExecuting"];
[strongSelf willChangeValueForKey:@"isFinished"];
strongSelf->finished = YES;
[strongSelf didChangeValueForKey:@"isFinished"];
});
}
- (NSString *) escapeHTML: (NSString *) aString
{
NSMutableString *s = [NSMutableString stringWithString:aString];
[s replaceOccurrencesOfString:@"\"" withString:@"&quot;" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
[s replaceOccurrencesOfString:@"&" withString:@"&amp;" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
[s replaceOccurrencesOfString:@"<" withString:@"&lt;" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
[s replaceOccurrencesOfString:@">" withString:@"&gt;" options:NSCaseInsensitiveSearch range:NSMakeRange(0, [s length])];
return [NSString stringWithString:s];
}
@end
@interface Cache ()
@property NSOperationQueue *cacheQueue;
@end
@implementation Cache
+ (instancetype)globalCache {
static id instance;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
instance = [[[self class] alloc] init];
[instance setupQueue];
});
return instance;
}
-(void) setupQueue
{
self.cacheQueue = [NSOperationQueue new];
}
- (void) cacheContents:(NSArray *)contents forHost: (NSString *)hostURL withCompletionBlock:(void (^)(NSError *, NSArray *))completionBlock
{
CacheOperation *cacheOperation = [[CacheOperation alloc] initWithContentsToCache:contents forHost:hostURL withComletionHandler:completionBlock];
[self.cacheQueue addOperation:cacheOperation];
}
@end
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