快速旋转/拾取器没有保存或显示整数

I'm trying to figure out why my spinner won't hold integers. When I run the program, question marks appear in the spinner instead of 1,2,3,4 and so on all the way up to 100. I'm new to Swift and this is my very first time working with the spinner/Picker. My program is supposed to calculate Miles per Gallon, but that can't happen if I can't get the spinner to work, lol.I'm trying to figure out why my spinner won't h