What does copy mean in Objective-C?

What does copy mean in Objective-C?

“The copy attribute is an alternative to strong. Instead of taking ownership of the existing object, it creates a copy of whatever you assign to the property, then takes ownership of that. Only objects that conform to the NSCopying protocol can use this attribute…”

What are the differences 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 the difference between retain and assign and when to use weak?

readonly. As far as I know, strong and retain are synonyms, so they do exactly the same. Then the weak is almost like assign , but automatically set to nil after the object, it is pointing to, is deallocated. That means, you can simply replace them.

What is the difference between atomic and non atomic synthesized properties?

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 assign in Objective-C?

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.

What is difference between shallow copy and deep copy in IOS?

A deep copy duplicates the objects referenced while a shallow copy duplicates only the references to those objects. So if object A is shallow-copied to object B, object B refers to the same instance variable (or property) that object A refers to.

What is assign property in Objective-C?

What is assign property?

An assignment is a legal term used in the context of the law of contract and of property. In both instances, assignment is the process whereby a person, the assignor, transfers rights or benefits to another, the assignee. The rights may be vested or contingent, and may include an equitable interest.

Which is faster shallow copy or deep copy?

Shallow Copy stores the copy of the original object and points the references to the objects. Deep copy stores the copy of the original object and recursively copies the objects as well. Shallow copy is faster. Deep copy is comparatively slower.

What is the difference between a deep copy and a shallow copy?

A shallow copy constructs a new compound object and then (to the extent possible) inserts references into it to the objects found in the original. A deep copy constructs a new compound object and then, recursively, inserts copies into it of the objects found in the original.

What is the difference between retain and assign in Swift?

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 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.

Should I always use the copy attribute when passing an NSString?

Yes – in general always use the copy attribute. This is because your NSString property can be passed an NSString instance or an NSMutableString instance, and therefore we can not really determine if the value being passed is an immutable or mutable object.

When should I specify “copy” in my @property declaration?

For attributes whose type is an immutable value class that conforms to the NSCopying protocol, you almost always should specify copy in your @property declaration. Specifying retain is something you almost never want in such a situation.

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.