自定义委托没有被调用？

Question

Actually I have three view controllers named in my app. I am navigating from A to B and then B to C. I am calling delegate method from C which is implemented in A. here is my code for

Ah

#import "A.h"
#import "C.h"

In Am I have

@interface A()<delegateName>
-(void)delegateMethod
{
  NSLog(@"delegate");
}
-(void)moveToB
{
  C *instanceOfC=[C alloc] init];
  instanceOfC.delegate=self;                //line 1
}

In Bh

#"import C.h"

In Bm

-(void)moveToC
{
  A *instanceOfA=[[A alloc] init];
  C *instanceOfC=[[C alloc] init];      
  instanceOfC.delegate= instanceOfA;            //line 2
}

In Ch

@protocal delegateName <NSObject>
-(void)delegateMethod;
@end
@interface C
@property(nonatomic,weak) id<delegateName>  delegate;
@end

In Cm

@synthesize delegate;
-(void)inSomeMethod
{
 [delegate delegateMethod];
}

if I put <delegateName> in Ah instead of Am then it says undeclared delegate .

Answer 1

In moveToC you are assigning instanceOfA to the delegate property of instanceOfC . At the end of moveToC both instances are deallocated, as you do not keep a strong reference to instanceOfC , eg assign it to a property.

You can fix this by adding a @property (strong, nonatomic) C *cInstance; to your Bm class and assign it when instantiating instanceOfC :

-(void)moveToC {
    A *instanceOfA=[[A alloc] init];
    self.cInstance = [[C alloc] init];
    self.cInstance.delegate= instanceOfA;
}

---

That said, the design looks wrong to me. I would rename delegateProtocol to somthing else, like DirtyJobHandler and introduce a custom init method in class C :

- (instanceType)initWithDirtyJobHandler:id<DirtyJobHandler> dirtyJobHandler {
    self = [super init];
    if (self) {
        self.dirtyJobHandler = dirtyJobHandler //previous knonw as self.delegate
    }
}

which is able to inject this dependency:

[[C alloc] initWithDirtyJobHandler:instanceOfA];

Answer 2

I think problem is in the line

A *instanceOfA=[[A alloc] init]; 

in the function

-(void)moveToC
{
 A *instanceOfA=[[A alloc] init];
 C *instanceOfC=[[C alloc] init];
 instanceOfC.delegate= instanceOfA;
 }

Replace the first line with

  A *instanceofA = self.navigationController.viewControllers[indexofA]

In B viewcontroller you are again allocate new memory for A viewcontroller and set the delegate to it. Instead of that you need to set the delegate which is previously in the memory and that can be find in two ways

(i) Get it from navigation controller (ii) Create a object of A viewcontroller in B viewcontroller.