修改AppDelegate Connection ReceiveResponse，处理续传时文件句柄为空。

RedAnt ERP Mobile/iSales-NPD/AppDelegate.m

@@ -2036,15 +2036,11 @@ void UncaughtExceptionHandler(NSException *exception) {
         DebugLog(@"%d begin",self.current_task);
         
         long long position=[self.download_task [[NSString stringWithFormat:@"item_%d",self.current_task]][@"position"] longLongValue];
-        if (position>0) {
-            //不需要创建文件；
-            return;
-        }
+        
         
         //获取下载文件大小
         //        self.fileLength = response.expectedContentLength;
         NSMutableDictionary* currenttask=[self.download_task [[NSString stringWithFormat:@"item_%d",self.current_task]] mutableCopy];
-        currenttask[@"fileLength"] = [NSNumber numberWithLongLong:response.expectedContentLength];
         
         
         //获取文件名
@@ -2063,6 +2059,15 @@ void UncaughtExceptionHandler(NSException *exception) {
         NSString* location=[NSString stringWithFormat:@"%@/%@",ver,response.suggestedFilename];
         NSString *filePath = [temp stringByAppendingPathComponent:location];
         DebugLog(@"save to: %@",filePath);
+        
+        if (position>0) {
+            //不需要创建文件；
+            //创建一个用来写数据的文件句柄
+            self.fileHandle = [NSFileHandle fileHandleForWritingAtPath:filePath];
+            return;
+        }
+        // 第一次获取的才是文件正确大小
+        currenttask[@"fileLength"] = [NSNumber numberWithLongLong:response.expectedContentLength];
         //创建一个空的文件到沙盒
         NSFileManager *fileManager = [NSFileManager defaultManager];
         [fileManager createFileAtPath:filePath contents:nil attributes:nil];