if Delegate sends gesture messages do they conform to my customised Objective C protocol?

问题

I am trying to send gesture messages from several subclassed UIViews to common handlers in a UIViewController called TouchController. I am using a customised protocol to address a question arising from the answer to my previous SO post.

Messages are now sent from OneOfSeveralSubviews using a customised protocol called FirstGestureRecognizerDelegate but none of the handlers respond even though the code compiles with 0 warnings. I am confident the problem is not in TouchController for reasons stated previously. And after looking at more references (below) and checking out possible duplicates (below) I am now looking for answers to a new set of questions.

See Note (below) for my response to a possible duplicate question.

Here is my customised protocol

OneOfSeveralSubviews.h

#import <UIKit/UIKit.h>

@protocol FirstGestureRecognizerDelegate <NSObject>

- (void)handleLongPress:(UILongPressGestureRecognizer*)gestureRecognizer;
- (void)handleTapSelect:(UITapGestureRecognizer*)gestureRecognizer;
- (void)handlePan:(UIPanGestureRecognizer*)gestureRecognizer;

@end

@interface OneOfSeveralSubviews : UIView
{
    CGRect touchFrame;
}

- (id)initView:(CGRect)rect;

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

@end

In the implementation of OneOfSeveralSubviews, gestures are defined by declaring instances of UILongPressGestureRecognizer, UITapGestureRecognizer and UIPanGestureRecognizer and setting their delegate properties

e.g.

UILongPressGestureRecognizer *longPressGR = [[UILongPressGestureRecognizer alloc] initWithTarget:(id)self.delegate 
                                                                                          action:@selector(handleLongPress:)];
[longPressGR setDelegate:(id)self.delegate];

The program runs but is unresponsive. I’m not sure if this happens because it [a] sends messages that conform to a protocol the handlers ignore OR [b] can’t find a way to send messages that conform to a protocol the handlers recognise. References I’ve looked at give no clue whether it is [a] or [b]. Moreover this document uses the term subclassing to mean something different to subclassing in my situation and the illustrated code examples are in Swift rather than Objective C.

This leads me to ask:

can UILongPressGestureRecognizer, UITapGestureRecognizer and UIPanGestureRecognizer actually be used with my customised protocol ?
or does a customised protocol also require customised gesture recognition methods rather than standard methods (i.e. pre-fixed with UI) ?
either way, are there simple code changes that would let the delegate send gesture messages that conform to the customised protocol ? or
is it possible I’m trying to do something that is conceptually flawed ?

I’d welcome answers to these questions or a better question if there is one.

OneOfSeveralSubviews.m

#import "OneOfSeveralSubviews.h"

@implementation OneOfSeveralSubviews

- (id)initView:(CGRect)rect
{
    self = [super initWithFrame:rect];
    if (self)
    {
        // Set view size and color

        UILongPressGestureRecognizer *longPressGR = [[UILongPressGestureRecognizer alloc] initWithTarget:(id)self.delegate action:@selector(handleLongPress:)];
        [longPressGR setDelegate:(id)self.delegate];
        [longPressGR setMinimumPressDuration:0.6f];
        [longPressGR setNumberOfTapsRequired:1];
        [longPressGR setNumberOfTouchesRequired:1];
        [hotspot addGestureRecognizer:longPressGR];

        // Create and configure two other gesture recognizers

        self.userInteractionEnabled = YES;
    }
    return self;
}

@end

TouchController.h

#import <UIKit/UIKit.h>
#import "OneOfSeveralSubviews.h"
#import "TwoOfSeveralSubviews.h"

// #import "ThreeOfSeveralSubviews.h"
// #import "FourOfSeveralSubviews.h"
//          etc.

@interface TouchController : UIViewController <FirstGestureRecognizerDelegate, SecondGestureRecognizerDelegate>
{
    CGRect touchFrame;
    CGRect screenFrame;
}

@property (strong, nonatomic) NSTimer *timer;

@end

TouchController.m

#import "TouchController.h"

@interface ViewController ()

@end

@implementation TouchController

- (void)viewDidLoad {
    [super viewDidLoad];

    OneOfSeveralSubviews *oneForAll=[[OneOfSeveralSubviews alloc] initView:[UIScreen mainScreen].bounds];
    [self.view addSubview:oneForAll];    
}

I've looked through these related posts:

Implementing a Custom Gesture Recognizer
UIGestureRecognizers
Working with protocols
Conventions
Avoid category method name clashes
Customizing Existing Classes
Handling app delegates and switching between views
differences between weak and assign property?

NOTE

I checked Scott’s duplicate question and it is definitely asking a question similar to those being asked here. But in Scott’s example it also looks as if delegation that originates inside the ViewController is destined for a target outside the Viewcontroller (i.e. in MakePlantTVC). Whereas in my case, delegation that originates outside the ViewController is destined for a target inside the ViewController. For that reason I would never have picked Scott’s question as a duplicate even though to a more experienced person such a difference might seem insignificant.

These possible duplicates are very similar but don't solve my problem:

Declare that delegate conforms to another protocol
How to conditionally conform to delegate protocol?
UIView setDelegate:]: unrecognized selector sent to instance

来源：https://stackoverflow.com/questions/49310512/if-delegate-sends-gesture-messages-do-they-conform-to-my-customised-objective-c

标签

ios

objective-c

delegates

protocols

uigesturerecognizer