I have never worked on non ARC based project. I just came across a zombie on my ARC based project. I found it was because of retain cycle.I am just wondering what is a retain cycle.Can
Could you give me an example for retain cycle?
A retain cycle is a situation when object A
retains object B
, and object B
retains object A
at the same time*. Here is an example:
@class Child;
@interface Parent : NSObject {
Child *child; // Instance variables are implicitly __strong
}
@end
@interface Child : NSObject {
Parent *parent;
}
@end
You can fix a retain cycle in ARC by using __weak
variables or weak
properties for your "back links", i.e. links to direct or indirect parents in an object hierarchy:
@class Child;
@interface Parent : NSObject {
Child *child;
}
@end
@interface Child : NSObject {
__weak Parent *parent;
}
@end