transferring large amounts of data, you are encouraged to set the value of this property to YES. Doing so lets the system schedule those transfers at times that are more optimal for the device. For example, the system might delay transferring large files until the device is plugged in and connected to the network via Wi- Fi. The default value of this property is NO. • ཁ: ͕Lightningέʔϒϧʹܨ͕͍ͬͯͯWi-FiΛར༻͢Δ·Ͱ େ͖ͳϑΝΠϧͷసૹΛͭ • https://developer.apple.com/library/ios/documentation/Foundation/Reference/NSURLSessionConfiguration_class/ index.html#//apple_ref/occ/instp/NSURLSessionConfiguration/discretionary