我正在将大量项目下载到NSArray中，因为我需要在本地将所有项目都用于离线目的，一旦将数据下载到NSURLSession竞争处理程序中的NSArray，我的应用程序的内存使用量相当适中大约120 MB，但是当我开始循环这个NSArray以将数据插入核心数据并在本地保存时，内存峰值非常快，然后由于内存问题导致应用程序终止。我已经尝试将NSArray拆分为数组的NSArray，以便在每个批处理保存到磁盘后尝试释放内存，但这也无济于事，所以我必须遗漏一些东西。我究竟做错了什么？我需要保持较低的内存占用率，以便我可以下载数据，并且它不是延迟加载的选项，只能下载所需的内容等，因为我必须提供离线方案，所以我绝对必须在本地拥有数据。
简而言之
完成处理程序启动循环时的内存使用量约为120 MB 然后它迅速增加到2 GB并且app终止 应用程序始终处于前台
我附上下载并保存数据的代码
+ (void)fetchTillDataAll:(int)tillId :(int)startAtRow :(int)takeNoOfRows {
if ([NWTillHelper isDebug] == 1) {
NSLog(@"WebServices:fetchTillDataAll:tillId = %d, startAtRow = %d, takeNoOfRows = %d", tillId, startAtRow, takeNoOfRows);
}
NSString *finalURL = [NSString stringWithFormat:@"https://host.domain.com/api/foo/bar];
[[[NSURLSession sharedSession] dataTaskWithURL:[NSURL URLWithString:finalURL]
completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
if (error != nil) {
if ([NWTillHelper isDebug] == 1) {
NSLog(@"WebServices:fetchTillDataAll:Transport error %@", error);
}
} else {
NSHTTPURLResponse *responseHTTP;
responseHTTP = (NSHTTPURLResponse *) response;
if(responseHTTP.statusCode != 200) {
if ([NWTillHelper isDebug] == 1) {
NSLog(@"WebServices:fetchTillDataAll:Server Error %d", (int) responseHTTP.statusCode);
}
} else {
NSArray *tillBasicDataArray = [NSJSONSerialization JSONObjectWithData:data
options:0
error:NULL];
if ([NWTillHelper isDebug] == 1) {
NSLog(@"WebServices:fetchTillDataAll:tillBasicDataArray count = %lu", (unsigned long)[tillBasicDataArray count]);
NSLog(@"WebServices:fetchTillDataAll:tillBasicDataArray looks like %@",tillBasicDataArray);
}
AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication]delegate];
NSPersistentContainer *container = appDelegate.persistentContainer;
NSArray *arrayOfArrays = [NWTillHelper splitIntoArraysOfBatchSize:tillBasicDataArray :1000];
for(NSArray *batch in arrayOfArrays) {
[container performBackgroundTask:^(NSManagedObjectContext *context ) {
context.mergePolicy = NSMergeByPropertyStoreTrumpMergePolicy;
NSDictionary *tillBasicDataDict = Nil;
/
/
for (id element in batch){
tillBasicDataDict = element;
NSString *itemId = [tillBasicDataDict objectForKey:@"itemId"];
NSString *brandId = [tillBasicDataDict objectForKey:@"companyId"];
NSString *languageId = [tillBasicDataDict objectForKey:@"languageCode"];
NSString *colorCode = [NSString stringWithFormat:@"%@", [tillBasicDataDict objectForKey:@"colorCode"]];
NSString *discountable = [tillBasicDataDict objectForKey:@"discountable"];
NSString *exchangeable = [tillBasicDataDict objectForKey:@"exchangeable"];
NSString *noos14 = [tillBasicDataDict objectForKey:@"noos14"];
NSString *sizeCode = [NSString stringWithFormat:@"%@", [tillBasicDataDict objectForKey:@"sizeCode"]];
NSString *taxGroup = [tillBasicDataDict objectForKey:@"taxGroupId"];
NSString *taxRegion = [tillBasicDataDict objectForKey:@"taxRegion"];
NSString *tradeItemDesc = [tillBasicDataDict objectForKey:@"tradeItemDesc"];
NSString *withTax = [tillBasicDataDict objectForKey:@"withTax"];
NSString *status = [tillBasicDataDict objectForKey:@"status"];
/
NSManagedObject *newPimItem = Nil;
newPimItem = [NSEntityDescription
insertNewObjectForEntityForName:@"TillData"
inManagedObjectContext:context];
[newPimItem setValue:itemId forKey:@"itemId"];
[newPimItem setValue:brandId forKey:@"brandId"];
[newPimItem setValue:languageId forKey:@"languageCode"];
[newPimItem setValue:colorCode forKey:@"colorCode"];
[newPimItem setValue:discountable forKey:@"discountable"];
[newPimItem setValue:exchangeable forKey:@"exchangeable"];
[newPimItem setValue:noos14 forKey:@"noos14"];
[newPimItem setValue:sizeCode forKey:@"sizeCode"];
[newPimItem setValue:[NSNumber numberWithInt:[taxGroup intValue]] forKey:@"taxGroup"];
[newPimItem setValue:taxRegion forKey:@"taxRegion"];
[newPimItem setValue:tradeItemDesc forKey:@"tradeItemDesc"];
[newPimItem setValue:[NSNumber numberWithInt:[withTax intValue]] forKey:@"withTax"];
[newPimItem setValue:[NSNumber numberWithInt:[status intValue]] forKey:@"status"];
if ([NWTillHelper isDebug] == 1) {
NSLog(@"WebServices:fetchTillDataAll:ItemId in loop = %@", itemId);
NSLog(@"WebServices:fetchTillDataAll:newPimItem = %@", newPimItem);
NSLog(@"WebServices:fetchTillDataAll:CoreData error = %@", error);
}
}
NSError *error = nil;
if (![context save:&error]) {
NSLog(@"Failure to save context: %@\n%@", [error localizedDescription], [error userInfo]);
abort();
} else {
NSUserDefaults *tillUserDefaults = [NSUserDefaults standardUserDefaults];
[tillUserDefaults setInteger:1 forKey:@"hasTillData"];
[tillUserDefaults synchronize];
}
}];
}
}
}
}] resume];
}
NSArray拆分方法如下所示
+ (NSArray *) splitIntoArraysOfBatchSize:(NSArray *)originalArray :(int)batchSize {
NSMutableArray *arrayOfArrays = [NSMutableArray array];
for(int j = 0; j < [originalArray count]; j += batchSize) {
NSArray *subarray = [originalArray subarrayWithRange:NSMakeRange(j, MIN(batchSize, [originalArray count] - j))];
[arrayOfArrays addObject:subarray];
}
return arrayOfArrays;
}
----编辑----
我甚至尝试将下载分成1000个记录的批次，但这也无济于事。
while ( loopCount < numberOfLoops ) {
if([NWTillHelper isDebug] == 1) {
NSLog(@"%s loopCount = %d", __PRETTY_FUNCTION__, loopCount);
NSLog(@"%s startAtRow = %d", __PRETTY_FUNCTION__, startAtRow);
NSLog(@"%s records to fetch = %@", __PRETTY_FUNCTION__, recordsToFetchStr);
}
//[self fetchPricelistAll:(int)[NWTillHelper getPricelist] :0 :recordsToFetch];
[self fetchPricelistAll:(int)[NWTillHelper getPricelist] :startAtRow :batchSizeInt];
startAtRow = startAtRow + batchSizeInt;
loopCount++;
}
答案 0 :(得分：0)
我建议拆分Web服务响应以提供位数据。您可以从服务器下载位并将其作为文本文件保存在文档文件夹中。从文本文件中依次获取数据并将其保存在核心数据中。保存到核心数据完成后删除文件。
答案 1 :(得分：0)
我们可以按照以下方法
保存后我们可以调用reset方法一个上下文
[managedObjectContext reset];