You can switch between the last used apps by swiping on the bar at the bottom of your phone.
How to Switch between the last used apps
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Disable unwanted App Review Requests
You can disable unwanted App Review Requests by going to "Settings App Store" and deselecting "In-App Ratings & Reviews.
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10 iPhone Gestures and Shortcuts You Should Know
Essential iPhone shortcuts including back button navigation, three-finger gestures, cursor control, and text replacement