iOS Developers Should Avoid These 5 Common Mistakes

We’ve all made them

Photo by David Duarte Crespo on Unsplash

Memory management

We all want to avoid user frustration when creating our Apps. Retain cycles can cause crashes and slow performance for the end user, none of which is good to say the least. Instruments is a great tool to track these issues in existing (or new!) code.

In the following code (in a Playground, or similar) deinit isn’t called for either the Tutorial or Student class. The reason? It’s a memory cycle.

class Tutorial {
    private var students = [Student]()
    func enroll(_ student: Student) {
        students.append(student)
    }
    init() {
        print ("Tutorial initialized")
    }
    deinit {
        print ("Tutorial deinitialized")
    }
}

class Student {
    private var tutorial : Tutorial
    private var name : String
    init(tutorial: Tutorial, name: String) {
        print ("Tutorial initialized")
        self.tutorial = tutorial
        self.name = name
    }
    deinit {
        print ("Tutorial deinitialized")
    }
}

var computing : Tutorial? = Tutorial()
var dave : Student? = Student(tutorial: computing!, name: "Dave")
computing?.enroll(dave!)

computing = nil
dave = nil

Not testing on real devices