How to trust an app on iPhone: While the App Store has over a million apps, it isn't always that easy for an app to get on with it. Your iPhone would not think twice about trusting the App when you upload it from the Apple App Store. If Mobile Device Management (MDM) installs an app, trust is automatically created. When you manually download an app, you need to think twice and have to build trust manually. To manage the apps, Apple recommends that you use an MDM solution. This technique is safe and needs no user interaction.