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What is property in iOS?
Property attributes are special keywords to tell compiler how to generate the getters and setters. Here you specify two property attributes: nonatomic, which tells the compiler not to worry about multithreading, and retain, which tells the compiler to retain the passed-in variable before setting the instance variable.
What is willSet and didSet in Swift?
willSet is called just before the value is stored. didSet is called immediately after the new value is stored.
What is variable in iOS?
Variables are the “things” in your code, like numbers, text, buttons and images. Every bit of information your app uses, is stored in a variable or a constant. Knowing how variables work is the first step of learning iOS development.
What is variable property?
Define Variable Properties is designed to assist you in the process of assigning attributes to variables, including creating descriptive value labels for categorical (nominal, ordinal) variables. Define Variable Properties: Scans the actual data values and lists all unique data values for each selected variable.
What is lazy variable?
A lazy var is a property whose initial value is not calculated until the first time it’s called. It’s part of a family of properties in which we have constant properties, computed properties, and mutable properties.
What is instance in iOS?
An instance method is a method that’s only available on a particular instance of a class, only after said instance of the class has already been created. Class methods are common in convenience initializers, though. For example, instead of typing this: NSObject *newObject = [[NSObject alloc] init];
Did set and will set in Swift?
It will only get called whenever you set the property by assigning a new value to it. It will always get called even if you assign the same value to it multiple times. willSet and didSet both have a default parameters newValue and oldValue. These parameters are constants, hence you cannot mutate their values.
Will set VS did set Swift?
willSet is called just before the value is stored. didSet is called immediately after the new value is stored. So basically code performed in willSet will not have access to the newValue of the variable while it runs, whereas didSet will have access to it (since it’s “after it’s been set”).
Can variables be constant?
In an algebraic expression, x+y = 8, 8 is a constant value, and it cannot be changed. Variables: Variables are the terms which can change or vary over time. It does not remain constant, unlike constant. For example, the height and weight of a person do not remain constant always, and hence they are variables.