自定义委托方法未被调用

Question

Look at the following code.

In CusFormViewController.h

@interface CusFormViewController : CusBaseViewController

@protocol CusFormViewControllerDelegate <NSObject>
-(void)ticketCreated:(NSString*)ticketID;
-(void)ticketFormRenderingFinished;
@end

@property (nonatomic, weak) id<CusFormViewControllerDelegate> delegate;

In CusFormViewController.m

if ([self.delegate respondsToSelector:@selector(ticketFormRenderingFinished)])
    [self.delegate ticketFormRenderingFinished];

if ([self.delegate respondsToSelector:@selector(ticketCreated:)])
    [self.delegate ticketCreated:ticket_id];

In ViewController.m

#import "CusFormViewController.h"

@interface ViewController ()<CusFormViewControllerDelegate>

- (void)viewDidLoad {
    [super viewDidLoad];

    CusFormViewController *formVC = [[CusFormViewController alloc] init];
    [formVC setDelegate:self];
}

-(void)ticketCreated:(NSString*)ticketID{
    NSLog(@"ticket created.");
}
-(void)ticketFormRenderingFinished{
    NSLog(@"ticket form rendered.");
}

The ticketCreated & ticketFormRenderingFinished are not being called.

Answer 1

Most common reason for delegate method not being called is dealing with incorrect objects.

1. Ensure that CusFormViewController object created from ViewController is the same which you are presenting on screen and that the delegate is being set on the same object. I truly believe you are creating a new CusFormViewController object and setting delegate on that.
2. In CusFormViewController , before calling delegate, check the existence of delegate as well. This is a safety check, you can also put a NSLog statement to double check if your delegate exists or not. You are failing here.
3. If you are segueing from ViewController to CusFormViewController then you set delegate in prepareForSegue: and not in viewDidLoad .

As a side note, put a NSLog statement in viewDidLoad of your CusFormViewController and print self.delegate to check the property setting.

Answer 2

Your controller formVC is dealloced after the function viewDidLoad executed. Create strong reference on your formVC for example like this:

@interface ViewController ()<CusFormViewControllerDelegate>
{
    CusFormViewController *_formVC;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    _formVC = [[CusFormViewController alloc] init];
    [formVC setDelegate:self];
}

Answer 3

Hey try to create instance of CusFormViewController using below method
CusFormViewController * _formVC=[[UIStoryboard storyboardWithName:storyboardName bundle: nil]instantiateViewControllerWithIdentifier:@"IDENTIFIER_OF_YOUR_ CusFormViewController"];