What is the difference between strong and weak references in IOS?

What is the difference between strong and weak references in IOS?

strong is the default. An object remains “alive” as long as there is a strong pointer to it. weak specifies a reference that does not keep the referenced object alive. A weak reference is set to nil when there are no strong references to the object.

What is the difference between atomic and nonatomic properties 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 strong property in Objective-C?

strong (default) Strong just means you have a reference to an object and you will keep that object alive. As long as you hold that reference to the object in that property, that object will not be deallocated and released back into memory.

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 difference between strong and weak in Swift?

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 difference between assign and retain?

Assign creates a reference from one object to another without increasing the source’s retain count. Retain creates a reference from one object to another and increases the retain count of the source object.

What is retain in iOS?

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.

What’s a difference between copy and retain?

Retain increases the retain count of an object by 1 and takes ownership of an object. Whereas copy will copy the data present in the memory location and will assign it to the variable so in the case of copy you are first copying the data from a location assign it to the variable which increases the retain count.

What is difference between strong and weak entity explain with an example?

The Key Difference between Strong and Weak Entity is that a Strong Entity has a primary key whereas a Weak Entity does not have a primary key. Weak entity is dependent on a strong entity whereas a Strong entity is independent not dependent on any other.

What is the difference between strong and weak entities?

A strong entity is represented by single rectangle. A weak entity is represented by double rectangle. Relationship between two strong entities is represented by single diamond. Relationship between a strong and weak entity is represented by double diamond.

What is the difference between @property(retain) NSString *name and copy?

@property (nonatomic)NSString *name; retainis required when the attribute is a pointer to an object. The setter method will increase retain count of the object, so that it will occupy memory in autorelease pool. @property (retain)NSString *name; copyIf you use copy, you can’t use retain.

What is the use of @property(nonatomic)NSString *name?

@property (nonatomic)NSString *name; retain is required when the attribute is a pointer to an object. The setter method will increase retain count of the object, so that it will occupy memory in autorelease pool.

What is the difference between retain and strong getter methods?

strong is a replacement for retain. It comes with ARC. @property (nonatomic, strong) AVPlayer *player; getter=method If you want to use a different name for a getter method, it’s possible to specify a custom name by adding attributes to the property.

What is @list of attributes of @property Atomic?

List of attributes of @property atomic, nonatomic, retain, copy, readonly, readwrite, assign, strong, getter=method, setter=method, unsafe_unretained atomicis the default behavior.