The difference between OC __weak and __strong

1. First on the code

ID __weak obj=[[nsobject Alloc]init];    NSLog (@ "Weak reference self Address:%p", &obj);    NSLog (@ "Weak reference points to address:%p", obj);    ID __strong obj0=[[nsobject Alloc]init];    ID __weak obj1=obj0;    NSLog (@ "strong reference to its own address:%p", &obj0);    NSLog (@ "Weak reference self Address:%p", &obj1);    NSLog (@ "Strong reference point to address:%p", obj0);    NSLog (@ "Weak reference points to address:%p", obj1);       obj1=nil;//    Obj0=nil;    NSLog (@ "Weak reference is destroyed when the strongly typed variable points to address:%p", obj0);    NSLog (@ "weak reference destroy when weak type variable points to address:%p", obj1);

2. Running Results

3. When a strongly typed variable is set to nil, two variables point to null

4. This shows that when a strong reference is held on a variable, a weak reference simply points to the variable and does not own it.

The difference between OC __weak and __strong