iOS 捏合缩放和两指同时旋转

这是我的代码：

视图加载：

UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(pinch:)];
[self.canvas addGestureRecognizer:pinch];
pinch.delegate = self;

UIRotationGestureRecognizer *twoFingersRotate = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(pinchRotate:)];
[[self canvas] addGestureRecognizer:twoFingersRotate];

twoFingersRotate.delegate = self;

捏合和旋转代码：

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}

-(void)pinchRotate:(UIRotationGestureRecognizer*)rotate
{
    SMImage *selectedImage = [DataCenter sharedDataCenter].selectedImage;

    switch (rotate.state) 
    {
        case UIGestureRecognizerStateBegan:
        {
            selectedImage.referenceTransform = selectedImage.transform;
            break;
        }
        case UIGestureRecognizerStateChanged:
        {
            selectedImage.transform = CGAffineTransformRotate(selectedImage.referenceTransform, ([rotate rotation] * 55) * M_PI/180);
            break;
        }

        default:
            break;
    }
}

-(void)pinch:(UIPinchGestureRecognizer*)pinch
{
    SMImage *selectedImage = [DataCenter sharedDataCenter].selectedImage;
    [self itemSelected];

    switch (pinch.state) 
    {
        case UIGestureRecognizerStateBegan:
        {
            selectedImage.referenceTransform = selectedImage.transform;
            break;
        }
        case UIGestureRecognizerStateChanged:
        {
            CGAffineTransform transform = CGAffineTransformScale(selectedImage.referenceTransform, pinch.scale, pinch.scale);
            selectedImage.transform = transform;
            break;
        }

        default:
            break;
    }
}

我的旋转单独工作效果很好，我的秤单独工作也很好，但它们不能一起工作。一个总是有效，另一个则无效。当我实现 shouldRecognizeSimultaneouslyWithGestureRecognizer 时，这两个手势似乎相互对抗并产生不良结果。我缺少什么？ （是的，我已经实施了<UIGestureRecognizerDelegate>)

每次pinch:被调用时，您只需根据捏识别器的比例计算变换即可。每次pinchRotate:被调用时，您只需根据旋转识别器的旋转来计算变换。您永远不会将缩放和旋转合并为一个变换。

这是一个方法。给自己一个新的实例变量，_activeRecognizers:

NSMutableSet *_activeRecognizers;

初始化它在viewDidLoad:

_activeRecognizers = [NSMutableSet set];

使用一种方法作为操作both识别器：

- (IBAction)handleGesture:(UIGestureRecognizer *)recognizer
{
    SMImage *selectedImage = [DataCenter sharedDataCenter].selectedImage;

    switch (recognizer.state) {
        case UIGestureRecognizerStateBegan:
            if (_activeRecognizers.count == 0)
                selectedImage.referenceTransform = selectedImage.transform;
            [_activeRecognizers addObject:recognizer];
            break;

        case UIGestureRecognizerStateEnded:
            selectedImage.referenceTransform = [self applyRecognizer:recognizer toTransform:selectedImage.referenceTransform];
            [_activeRecognizers removeObject:recognizer];
            break;

        case UIGestureRecognizerStateChanged: {
            CGAffineTransform transform = selectedImage.referenceTransform;
            for (UIGestureRecognizer *recognizer in _activeRecognizers)
                transform = [self applyRecognizer:recognizer toTransform:transform];
            selectedImage.transform = transform;
            break;
        }

        default:
            break;
    }
}

您将需要这个辅助方法：

- (CGAffineTransform)applyRecognizer:(UIGestureRecognizer *)recognizer toTransform:(CGAffineTransform)transform
{
    if ([recognizer respondsToSelector:@selector(rotation)])
        return CGAffineTransformRotate(transform, [(UIRotationGestureRecognizer *)recognizer rotation]);
    else if ([recognizer respondsToSelector:@selector(scale)]) {
        CGFloat scale = [(UIPinchGestureRecognizer *)recognizer scale];
        return CGAffineTransformScale(transform, scale, scale);
    }
    else
        return transform;
}

如果您只允许旋转和缩放，则此方法有效。 （我什至测试过！）

如果要添加平移，请使用单独的操作方法，然后调整即可selectedImage.center。尝试使用旋转和缩放进行平移selectedImage.transform情况要复杂得多。