Schemetrical questions

Schemetrical answers

• Update to Xcode 6.3 breaks app - Google GTLTouchStaticLib "not equal to a null pointer is always true"
• Swift - what is downcasting? why do i need to downcast the cell in tableview?
• How to check if a constraint already exists inside a view?
• Properties and Allocating Memory
• Use of unresolved identifier NSCalendarUnitDay
• Advantages of setting Constraints vs Setting Frames of UIViews
• "No provisioned iOS devices are available with a compatible iOS version" after upgrade
• In Swift 4.1 how do you request write-only permission for the photo library?
• Open Settings warning issue in Xcode 6.3: Comparison of address of 'UIApplicationOpenSettingsURLString' not equal to a null pointer is always true
• In custom iOS keyboard detect the app