UIView/Drawer using Pan/Swipe Gesture - ios

Question

I am trying to make a UIView open & close on Swipe/Pan Gesture & i found some help from following link
Link , it's close to what i m trying to make.
I want UIView to be open by 100 pixels default & User can swipe/pan the UIView using gesture till 75% of the parent UIViewController & back to 100 pixels but it's flicking in this below code. I want UIView's X position to be 0 so it can be like a drawer opening from top.
- (void)viewDidLoad {
[super viewDidLoad];
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:#selector(move:)];
drawerView = [self.storyboard instantiateViewControllerWithIdentifier:#"drawerVC"];
[drawerView.view setFrame:CGRectMake(0, -self.view.frame.size.height + 100, self.view.frame.size.width, self.view.frame.size.height * 0.75)];
[drawerView.view setBackgroundColor:[UIColor redColor]];
[drawerView.view addGestureRecognizer:panGesture];
}
-(void)move:(UIPanGestureRecognizer*)recognizer {
recognizer.view.center = CGPointMake(self.view.frame.size.width/2,
recognizer.view.center.y + translation.y);
[recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
if (recognizer.state == UIGestureRecognizerStateEnded) {
CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y));
CGFloat slideMult = magnitude / 200;
NSLog(#"magnitude: %f, slideMult: %f", magnitude, slideMult);
float slideFactor = 0.1 * slideMult; // Increase for more of a slide
CGPoint finalPoint = CGPointMake(0,
recognizer.view.center.y + (velocity.y * slideFactor));
finalPoint.x = 0;
finalPoint.y = MIN(MAX(finalPoint.y, 0), drawerView.view.frame.size.height*.75);
if (fabs(recognizer.view.frame.origin.y) >= fabs(yOffset))
{
return;
}
NSLog(#"ended %f",finalPoint.y);
if (finalPoint.y < recognizer.view.frame.size.height/2) {
// [self movePanelToOriginalPosition];
}
else{
[self movePanelToCenterPosition];
}
}
}
-(void)movePanelToCenterPosition {
[UIView animateWithDuration:0.3 delay:0 options:UIViewAnimationOptionCurveEaseIn animations:^{
drawerView.view.frame = CGRectMake(0, 0, drawerView.view.frame.size.width, drawerView.view.frame.size.height);
}
completion:^(BOOL finished) {
// Stuff to do
}];
}
Is there anything that can prevent user to pan UIView in Top(Up) direction if UIView is at default(100 pixels) & can only swipe down to desired CGPoint.

Answer 1

In your move: method you check if the move start or is in progress
else if (recognizer.state == UIGestureRecognizerStateBegin || recognizer.state == UIGestureRecognizerStateChanged)" and in the if view is at its limit. if so you can disabled/reenabled the gesture recognizer. This will cancel the pan...
- (void) move:(UIGestureRecognizer *)sender
{
if(sender.state == UIGestureRecognizerStateBegan || sender.state == UIGestureRecognizerStateChanged)
{
BOOL shouldEnablePan = NO; // TODO: do some logic here to figure out if you want to allow pan
if(!shouldEnablePan && [sender isKindOfClass:[UIPanGestureRecognizer class]])
{
sender.enabled = NO;
sender.enabled = YES;
}
} else ...
}