What is strong weak in IOS?
strong: assigns the incoming value to it, it will retain the incoming value and release the existing value of the instance variable. weak: will assign the incoming value to it without retaining it.
What is the difference between strong and weak references in IOS?
A weak reference is just a pointer to an object that doesn’t protect the object from being deallocated by ARC. While strong references increase the retain count of an object by 1, weak references do not. This ensures that when you access a weak reference, it will either be a valid object, or nil.
What is Nonatomic strong?
In non-ARC code strong is just a synonym for retain. A variable maintains a strong reference to an object only as long as that variable is in scope, or until it is reassigned to another object or nil. Example.
What is difference between strong and weak?
The key difference between a strong and a weak or unowned reference is that a strong reference prevents the class instance it points to from being deallocated. In other words, weak and unowned references cannot prevent a class instance from being deallocated.
What is weak and strong in IOS Swift?
In Swift, strong references are the default, so to make a reference weak you can use the weak keyword. Unlike strong references, a weak reference does not affect an instance’s retain count. It does not hold onto the object. In short, a strong reference cycle or “retain cycle” is 2 instances holding onto each other.
What is weak and unowned IOS?
The main difference between weak and unowned is that weak is optional while unowned is non-optional. By declaring it weak you get to handle the case that it might be nil inside the closure at some point. If you try to access an unowned variable that happens to be nil, it will crash the whole program.
Why do we use weak in Swift?
The only reason you need to use weak in Swift coding is to avoid strong reference cycles. In short, a strong reference cycle or “retain cycle” is 2 instances holding onto each other. They cannot be removed from memory, which causes a memory leak, which could crash your app, which is a bad user experience.
What is difference between atomic and nonatomic in IOS?
Atomic means only one thread accesses the variable (static type). Atomic is thread-safe, but it is slow. Nonatomic means multiple threads access the variable (dynamic type). Nonatomic is thread-unsafe, but it is fast.
What is Nonatomic Objective-C?
thread unsafe mode
Nonatomic means “thread unsafe mode” and is (in a word) now totally irrelevant.
What is strong and weak IOS Swift?
April 21, 2018. A strong reference means that you want to “own” the object you are referencing with this property/variable. In contrast, with a weak reference you signify that you don’t want to have control over the object’s lifetime.
What is weak in IOS Swift?
Weak References. A weak reference is a reference that doesn’t keep a strong hold on the instance it refers to, and so doesn’t stop ARC from disposing of the referenced instance. This behavior prevents the reference from becoming part of a strong reference cycle.
What is lazy VAR?
A lazy var is a property whose initial value is not calculated until the first time it’s called. A lazy stored property is a property whose initial value is not calculated until the first time it is used. You indicate a lazy stored property by writing the lazy modifier before its declaration.