How are the file names assigned when taking photos in iOS 10?

Using iPhone 6s to take photos in iOS10. Software assigns a file name to each photo (i.e.; IMG_1234.jpg). These 4 digit numbers do not corospond to any time sequence. As a result when I import into a folder in mac OS Sierra they appear in random time order. I have looked in iOS settings and can not see a way to put them in time taken order nor can I find a way to sort them into that order in finder??? Any ideas???

Regards,

Denis