如何降低双指缩放 UIGestureRecognizer 的速度

Question

我创建了一个UIGestureRecognizer很像this one：

- (void)handlePinchGesture:(UIPinchGestureRecognizer *)gestureRecognizer {

    if([gestureRecognizer state] == UIGestureRecognizerStateBegan) {
        // Reset the last scale, necessary if there are multiple objects with different scales
        lastScale = [gestureRecognizer scale];
    }

    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || 
        [gestureRecognizer state] == UIGestureRecognizerStateChanged) {

        CGFloat currentScale = [[[gestureRecognizer view].layer valueForKeyPath:@"transform.scale"] floatValue];

        // Constants to adjust the max/min values of zoom
        const CGFloat kMaxScale = 2.0;
        const CGFloat kMinScale = 1.0;

        CGFloat newScale = 1 -  (lastScale - [gestureRecognizer scale]); 
        newScale = MIN(newScale, kMaxScale / currentScale);   
        newScale = MAX(newScale, kMinScale / currentScale);
        CGAffineTransform transform = CGAffineTransformScale([[gestureRecognizer view] transform], newScale, newScale);
        [gestureRecognizer view].transform = transform;

        lastScale = [gestureRecognizer scale];  // Store the previous scale factor for the next pinch gesture call  
    }
}

这按预期工作，但是我的客户希望它对触摸不那么敏感。如何降低捏合的速度（向内和向外），使其以默认速度的 80% 左右缩放？

Answer 1

您是否尝试过将scale当前值调至 80%？

if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || 
        [gestureRecognizer state] == UIGestureRecognizerStateChanged) {

    CGFloat maxScale = 2.0;
    CGFloat currentScale = [gestureRecognizer scale];
    currentScale = 0.8 * currentScale;   //80% of scaling

    if(currentScale < 0.8)
        currentScale = 0.8;

    if(currentScale > maxScale)
        currentScale = maxScale;

    [gestureRecognizer view].transform = CGAffineTransformScale([[gestureRecognizer view] transform], currentScale, currentScale);

}