E.g. the "gearshape" or "gear" symbol, they are very close to the title, whereas the "function" symbol is far away.
It only seems to be a few pixels, but both next to each other look pretty bad.
I created a TabBarController, with 4 child views, with Bar item icons as function
gear
rectangle and pencil and ellipsis
square and arrow up
All icons are aligned on top
All labels are aligned
But icons have different size, so effectively, func and rectangle appeared shifted to the top.
Read this, may be a solution to your problem
https://stackoverflow.com/questions/10533917/ios-5-custom-tab-bar-image-vertical-alignment
Note I tested as described there, both in code of the VC viewDidload
tabBarItem.imageInsets = UIEdgeInsets(top: 6, left: 0, bottom: -6, right: 0)
or in IB by setting the insets.
But could not get any change
I also tested this in viewDidLoad, to no avail
				for tab in self.tabBarController!.tabBar.items! {
						tab.imageInsets = UIEdgeInsets(top: 6, left: 0, bottom: -6, right: 0)
				}
I also tested this, but could not get the result they show to move the icon:
https://stackoverflow.com/questions/16285205/moving-uitabbaritem-image-down