I know about the HTTPMaximumConnectionsPerHost option on NSURLSessionConfiguration... but how many connections can iOS handle irrespective of host?
I assume this depends on some combination of... the # of cores.. the network interface.. and how busy the OS is in general + with downloads for other applications.
Can't find any hints about this.
Regardless I assume it's ridiculous to expect more than 2 or 3 at once..
Edit
Assuming the ability to have as many hosts and NSURLSession instances as wanted
You can set more than 1000. As you know, Apples's document doesn't specify upper limit.
To download about 2000 small files in background, I set httpMaximumConnectionsPerHost to 2000, and tested w/ iPhone7+/iOs10.3.1 under WiFi. It worked w/o any issue. Then, I tested download time by changing
httpMaximumConnectionsPerHost, and realized that increasing the number doesn't necessarily buy download time. So, for now, I'm leaving it to default value (=4). I think you need to examine with your apps (number of files, size, etc.).
