In the interface builder, you can select the navigation item of the previous controller and change the Back Button
string to what you'd like the back button to appear as. If you want it blank, for example, just put a space.
You can also change it with this line of code:
[self.navigationItem.backBarButtonItem setTitle:@"Title here"];
Or in Swift:
self.navigationItem.backBarButtonItem?.title = ""
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