You send an object a retain message when you want to prevent it from being deallocated until you have finished using it. An object is deallocated automatically when its reference count reaches 0 . retain messages increment the reference count, and release messages decrement it.

No, a copied object will have a retain count of 1, just like a newly initialized object. I highly recommend you read the Memory Management Guide if you wish to learn more. If you’re new to iOS development, the iOS App Programming Guide should be read first, and is a great use of your time.

strong / retain : Declaring strong means that you want to “own” the object you are referencing. Any data that you assign to this property will not be destroyed as long as you or any other object points to it with a strong reference.

If your @synthesize statement doesn’t explicitly associate an instance variable name with the property, then it will use a variable name without a leading underscore. So: @synthesize firstName; The compiler will provide the pieces (instance variable, getter, setter) that you do not.

Properties in Objective-C are used to store data in instances of classes. They define memory management, type, and access attributes of the values they store such as strong , weak , assign , readonly , readwrite , etc.

Properties associate values with a particular class, structure, or enumeration. Stored properties store constant and variable values as part of an instance, whereas computed properties calculate (rather than store) a value. Computed properties are provided by classes, structures, and enumerations.

An instance of a class is traditionally known as an object. However, Swift structures and classes are much closer in functionality than in other languages, and much of this chapter describes functionality that applies to instances of either a class or a structure type.

assign -assign is the default and simply performs a variable assignment -assign is a property attribute that tells the compiler how to synthesize the property’s setter implementation -I would use assign for C primitive properties and weak for weak references to Objective-C objects.

copy Makes a copy of an object, and returns it with retain count of 1. If you copy an object, you own the copy. This applies to any method that contains the word copy where “copy” refers to the object being returned. retain Increases the retain count of an object by 1.

Use classes if you want reference types. Use structs if you want value types. Even though struct and enum don’t support inheritance, they are great for protocol-oriented programming. A subclass inherits all the required and unwanted functionalities from the superclass and is a bad programming practice.

In order to modify the properties of a value type, you have to use the mutating keyword in the instance method. With this keyword, your method can then have the ability to mutate the values of the properties and write it back to the original structure when the method implementation ends.

It clearly states that adding mutating keyword to any function in value type can enable them to modify the variable. Internally when we try to mutate the value type, it does not mutate its value but it mutates the variable holding that value.

Peter Steinberger. iOS Development Swift. Swizzling (other languages call this “monkey patching”) is the process of replacing a certain functionality or adding custom code before the original code is called. For example, you could swizzle UIViewController.

verb (used with object), mu·tat·ed, mu·tat·ing. to change; alter. Biology. to cause (a gene, cell, etc.) to undergo an alteration of one or more characteristics: The disease mutates the retina’s rod cells, and they slowly stop working.

With the introduction of Swift, there are multiple ways to write such functions. Static functions are invoked by the class itself, not by an instance. This makes it simple to invoke utility functions without having to manage an object to do that work for you. Static functions can not be overridden.

Static variables are those variables whose values are shared among all the instance or object of a class. When we define any variable as static, it gets attached to a class rather than an object. You create static variable by appending static keyword in front of your variable declaration. …

You call instance methods with the same dot syntax as properties: let counter = Counter()…Instance Methods

1. class Counter {
2. var count = 0.
3. func increment() {
4. count += 1.
5. }
6. func increment(by amount: Int) {
7. count += amount.
8. }

Type methods are defined on a specific type like a structure, enum, class or even the predefined types like int, string, double, etc, but for those we need to dive into extensions (which I will do in a future post). They are available to the type itself, without being necessary to create an instance of that type.

: the practice of basing the name of a taxon upon a type and accepting as validly published only those names so based.

The instance method defined in my class is area . Now, a type method is a method that can be called directly on the type without creating an instance of that type. This indicates that it pertains to the type directly and not to an instance of the type. Difference between class method and instance method?

Some folks use “function” and “method” interchangeably, but there’s a small difference: both of them are reusable chunks of code, but methods belong to classes, structs, and enums, whereas functions do not. This is a special value passed in by Swift, and it refers to whatever instance the method was called on.

A method, like a function, is a set of instructions that perform a task. The difference is that a method is associated with an object, while a function is not.

Which research method should I choose?

• Observation / Participant Observation.
• Surveys.
• Interviews.
• Focus Groups.
• Experiments.
• Secondary Data Analysis / Archival Study.
• Mixed Methods (combination of some of the above)