what is diff. b/w @property (nonatomic,assign) and @property (nonatomic,retain) [duplicate]

Answer 1

The meanings of these keywords are related to the memory management implemented by the property:

• retain: the object will retain a new value set for its property, and will release old values
• copy: the object will take a copy of the new value, and will release the old value
• assign: the object will not do any memory management of its property value.

See "setter semantics" in the Objective-C language documentation.

In an automatic reference counting scenario, the following memory management keywords are used:

• strong: the object keeps a strong (i.e. owning) reference to its property
• weak: the object keeps a zeroing weak reference to its property