ios - 如果忽略“UIGestureRecognizerDelegate”的重复协议(protocol)定义，如何定义目标

Question

更新2

即使问题仍然存在，当前形式的问题也已得到回答和接受。该代码现在以0警告进行编译，但仍然对手势无响应。解决问题后，将希望通过准备新问题的过程来更新代码。一个新问题已发布here。

据我所知，在我所阅读的任何帖子中都从未问过或回答过这个问题(请参阅下面的重复内容)。

我正在尝试编写Objective C测试代码，以从iPhone屏幕上由矩形UIView定义的任何区域中长按，点击或移动消息。到目前为止，如果UILongPressGesture,和handler方法都位于UITapGesture中，则我可以使用UIPanGesture UIView或UIViewController可靠地发送离散或连续消息。

最终，我想将手势消息从多个子类的UIViews发送到UIViewController中的常见处理程序，但是在尝试执行此操作时遇到了问题。在编写代码时，我研究了有关使用UIGestureRecognition的委托以及Touchs中的Objective C方法(请参阅下面的注释)和SO帖子中的示例(下面的链接)一起使用的Apple文档。

该代码无法响应手势输入。最初，它编译时包含四个警告和两个问题:

重复协议

“UIGestureRecognizerDelegate”的重复协议定义为
被忽略


更新1

现在已经解决了这一问题。 Paul’s answer阐明了到目前为止我还不了解的一点。作为回应，我在本文中更改了协议的名称，测试了代码并对其进行了更新。

在 OneOfSeveralSubviews.h中，该协议现在称为 FirstGestureRecognizerDelegate.。已在 ViewController中进行了相关更改，例如

@interface ViewController : UIViewController <FirstSubviewGestureDelegate, SecondSubviewGestureDelegate>

未声明的选择器。

通过将委托属性键入(即，插入 id(建议为 here))，对三个手势声明(即 initWithTarget:(id)self)进行了类似的更改，并在每个 self实例中添加了一个委托属性，从而将三个警告静音了，从而将消息发送到预期的目标-即 (id)self.delegate而不是 (id)self
该代码先前编译时带有一个警告，但对手势没有任何响应。

更新2

该代码现在以0警告进行编译，但仍然对手势无响应。

我对照 here列出的四个要点(即 userInteractionEnabled， minimumPressDuration， numberOfTapsRequired和 numberOfTouchesRequired)检查了代码，并确保在 UIViewController.h.中指定委托

我的第一个问题已经回答

Q.1接口中的协议定义如何是 duplicate？

这两个问题有待回答

Q.2如果默认情况下已经存在UIGestureRecognizer协议，那么我该如何定义将处理手势消息的目标？要么

Q.3如何定义不是 self而是ViewController中的方法的委托目标？

我相信，有更多经验的人可以认出答案，并解释我还没有做的事情，或者提出一些可以使问题更加清晰的问题。谢谢您的期待。

对于需要在 objective-c 中工作的人，他们需要更多地了解代表-一些人的过往知识，但仍然是试图追赶的黑手(像我一样:-)的前沿领域，这对图例的解释也会有所帮助。

格雷格

更新2

如果从 .delegate手势声明中删除了 handleTap:属性，并且点击了红色方块，则程序将崩溃，并显示以下日志:
[OneOfSeveralSubviews handleTapSelect:] : unrecognized selector sent to instance 0x7fbe27d064b0
如果还从 .delegate或 handleLongPress:手势声明中删除了 handlePan:属性，则会出现类似的崩溃日志。

代码的第一部分是ViewController(下面)，它包含三个目标方法，分别称为(1) handleLongPress:(2) handleTapSelect:和(3) handlePan:
ViewController.m

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

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

( method 1)

- (void)handleLongPress:(UILongPressGestureRecognizer*)gestureRecognizer
{
    if (gestureRecognizer.state == UIGestureRecognizerStateBegan)
    {
        NSLog(@"started");
        self.timer=[NSTimer scheduledTimerWithTimeInterval:1.0
                                                    target:self
                                                  selector:@selector(stillPressing:)
                                                  userInfo:nil
                                                   repeats:YES];
    } else if (gestureRecognizer.state == UIGestureRecognizerStateEnded)
    {
        [self.timer invalidate];
        self.timer = nil;
        NSLog(@"ended");
    }
}

    - (void)stillPressing:(NSTimer *)timer
    {
        NSLog(@"pressing");
    }

(方法2)

- (void)handleTapSelect:(id)sender
{
    NSLog(@"tapped");
}

( method 3)

 - (void)handlePan:(UIPanGestureRecognizer*)gestureRecognizer
{
    [self adjustAnchorPointForGestureRecognizer:gestureRecognizer];

    UIView *piece = [gestureRecognizer view];

    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {
        CGPoint translation = [gestureRecognizer translationInView:[piece superview]];

        [piece setCenter:CGPointMake([piece center].x + translation.x, [piece center].y + translation.y)];
        [gestureRecognizer setTranslation:CGPointZero inView:[piece superview]];

        NSLog(@"%f %f", translation.x, translation.y);

        [UIView animateWithDuration:0.75
                              delay:0
             usingSpringWithDamping:0.75
              initialSpringVelocity:0
                            options:UIViewAnimationOptionCurveLinear
                         animations:^{

                          piece.frame = touchFrame;
                      }
                            completion:^(BOOL finished) {
                     }];
    }
}


- (void)adjustAnchorPointForGestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
{
    if (gestureRecognizer.state == UIGestureRecognizerStateBegan) {
        UIView *piece = gestureRecognizer.view;
        CGPoint locationInView = [gestureRecognizer locationInView:piece];
        CGPoint locationInSuperview = [gestureRecognizer locationInView:piece.superview];

        piece.layer.anchorPoint = CGPointMake(locationInView.x / piece.bounds.size.width, locationInView.y / piece.bounds.size.height);
        piece.center = locationInSuperview;
    }
}

ViewController.h

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

@interface ViewController : UIViewController <FirstSubviewGestureDelegate, SecondSubviewGestureDelegate>
{
    CGRect touchFrame;
}

@property (strong, nonatomic) NSTimer *timer;

@end

OneOfSeveralSubviews.m

#import "OneOfSeveralSubviews.h"

@implementation OneOfSeveralSubviews

- (id)initView:(CGRect)rect
{
    self = [super initWithFrame:rect];
    if (self)
    {
        CGFloat width = [UIScreen mainScreen].bounds.size.width;
        CGFloat height = [UIScreen mainScreen].bounds.size.height;
        CGPoint screenCentre = CGPointMake(width*0.5, height*0.5);

        CGFloat fullSide = width * 0.33;
        CGFloat halfSide = fullSide * 0.5;

        touchFrame = CGRectMake(screenCentre.x - halfSide, screenCentre.y - halfSide, fullSide, fullSide);
        UIView *hotspot = [[UIView alloc] initWithFrame:touchFrame];
        hotspot.backgroundColor = [UIColor redColor];

        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];

        UITapGestureRecognizer *tapGR = [[UITapGestureRecognizer alloc] initWithTarget:(id)self.delegate action:@selector(handleTapSelect:)];
        [tapGR setDelegate:(id)self.delegate];
        [tapGR setNumberOfTapsRequired:1];
        [tapGR setNumberOfTouchesRequired:1];
        [hotspot addGestureRecognizer:tapGR];
        [self addSubview:hotspot];

        UIPanGestureRecognizer *panGR = [[UIPanGestureRecognizer alloc] initWithTarget:(id)self.delegate action:@selector(handlePan:)];
        [panGR setDelegate:(id)self.delegate];
        [panGR setMinimumNumberOfTouches:1];
        [panGR setMaximumNumberOfTouches:1];
        [hotspot addGestureRecognizer:panGR];

        self.userInteractionEnabled = YES;
    }
    return self;
}

@end

OneOfSeveralSubviews.h

#import <UIKit/UIKit.h>

@protocol FirstSubviewGestureDelegate <NSObject>

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

@end

@interface OneOfSeveralSubviews : UIView
{
    CGRect touchFrame;
}

- (id)initView:(CGRect)rect;

@property (assign) id<FirstSubviewGestureDelegate> delegate;

@end

链接

What is meant by .delegate=self?

What are the differences between delegates and events ?

Why are Objective-C delegates usually given the property assigninstead of retain?

when to use respondsToSelector in objective-c

Objective C responds to selector

iOS - UILongPressGestureRecognizer

Using UILongPressGestureRecognizer and UISwipeGestureRecognizer

Using UILongPressGestureRecognizer For Subviews of UIScrollview

可能重复的

Duplicate protocol definition warning, but I need multiples of this
protocol

warning: duplicate protocol definition of '…' is ignored

Duplicate protocol definition

Duplicate protocol definition warning

Handling app delegates and switching between views

注意

关于 handling gestures的Apple文档包括Swift中的示例。如果您在Objective C中工作，请参考 Touches，但请记住，它不再在“早于iOS 7”的版本上编译。如果您能够为Objective C程序员提供更有用的参考，请编辑此注释。

Answer 1

UIGestureRecognizerDelegate由UIKit声明。您不能创建自己的名为UIGestureRecognizerDelegate的协议；这是一个相互矛盾的声明。

按照约定，带有UI前缀的类和协议由UIKit声明，并且您不应使用此前缀声明自己的对象和类。使用类似MyGestureRecognizerDelegate的东西