I am currently adding images to each one of my tab bar items. One image I like has a size that is much bigger then the area of the bar item. When I set the image of the bar
Another option is to create a vector image PDF. What you do is resize your vector image to the smallest size (22x22) and export it to a PDF file. You can do this with Adobe Illustrator, Sketch and many other vector image editing tools.
Then you add the PDF file to your assets folder and in the Properties Inspector set "Scale Factors" to "Single Vector". That should do it!