Check if app_key is in storage before initInstance
Check if app_key is in storage before initInstance

BranchMetrics/ios-branch-deep-linking,BranchMetrics/iOS-Deferred-Deep-Linking-SDK,BranchMetrics/iOS-Deferred-Deep-Linking-SDK,BranchMetrics/ios-branch-deep-linking,BranchMetrics/ios-branch-deep-linking,BranchMetrics/ios-branch-deep-linking