UIView Swipe Animation Glitches

Question

I am trying to add swipe to change view to my tabbar application. Like a page view.

So far my solution is working but I get glitches while swiping, I assume those are view.frame (CGRectMake) changes causing those black glitches but I havent figure out why it is happening.

It doesn't happen in device a bad as simulator but still visible and not smooth.

so in my root tabbar controller (TabViewController : UITabBarController)

#import <QuartzCore/QuartzCore.h>

#define XCTabViewDummyNSUintegerNOTargetVC 10
#define XCTabViewSwipeYAxisMax 40
#define XCTabViewSwipeXAxisMax 40

@interface XCTabViewController ()
@property (nonatomic, strong) id<XCTabControlStrategy> tabStrategy;
@property double swipeRatio;
@property double toViewX;
@property double fromViewX;

@property UIView * fromView;
@property UIView * toView;
@end

then

-(void)viewDidAppear:(BOOL)animated
{
    XCDeviceType deviceType = [UIViewUtils currentDeviceType];

    swipeRatio = 320;

    switch (deviceType) {

        case XCiPhone4:
            swipeRatio = 320;
            break;

        case XCiPhone5:
            swipeRatio = 320;
            break;

        case XCiPhone6:
            swipeRatio = 375;
            break;

        case XCiPhone6Plus:
            swipeRatio = 414;
            break;

        default:
            swipeRatio = 320;
            break;
    }

    // add pan recognizer to the view when initialized
    UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panRecognized:)];
    [panRecognizer setDelegate:(id)self];
    [self.view addGestureRecognizer:panRecognizer]; // add to the view you want to detect swipe on

}

then

-(void)panRecognized:(UIPanGestureRecognizer *)sender{

    CGPoint distance = [sender translationInView: self.view];

    if (sender.state == UIGestureRecognizerStateChanged) {

        if (distance.x > XCTabViewSwipeXAxisMax && distance.y > -XCTabViewSwipeYAxisMax && distance.y < XCTabViewSwipeYAxisMax) { // right
            [sender cancelsTouchesInView];
            NSLog(@"user swiped right");
            NSLog(@"swipe direction \n ---------------->"); //view on the left should be displayed
            NSLog(@"distance.x  %f", distance.x);
            if (self.selectedIndex >= 1 ) {
                NSUInteger targetVc = self.selectedIndex - 1;
                // Get the views.
                fromView = self.selectedViewController.view;
                toView = [[self.viewControllers objectAtIndex:targetVc] view];

                // Get the size of the view area.
                CGRect viewSize = fromView.frame;

                // Add the to view to the tab bar view.
                [fromView.superview addSubview:toView];

                // Position it off screen.
                toView.frame = CGRectMake(-swipeRatio, viewSize.origin.y, swipeRatio, viewSize.size.height);


                [UIView animateWithDuration:0 animations:^{
                    // Animate the views on and off the screen. This will appear to slide.
                    fromView.frame =CGRectMake(distance.x, viewSize.origin.y, swipeRatio, viewSize.size.height);
                    toView.frame =CGRectMake(-swipeRatio+distance.x, viewSize.origin.y, swipeRatio, viewSize.size.height);

                    toViewX = -swipeRatio+distance.x;
                    fromViewX = distance.x;

                }];


            }

       }
} 

How can I make this animation smoother?

Also on intense swiping I get memory warnings.

Answer 1

Turns out problem was in this line

// Position it off screen. toView.frame = CGRectMake(-swipeRatio, viewSize.origin.y, swipeRatio, viewSize.size.height);

positioning toView off screen everytime distance.x changes was causing that glitches

here is my full solution

    NSLog(@"user swiped right");
    NSLog(@"swipe direction \n ---------------->"); //view on the left should be displayed
    NSLog(@"distance.x  %f", distance.x);
    if (self.selectedIndex >= 1 ) {
        NSUInteger targetVc = self.selectedIndex - 1;

        // Get the views.
        if (!fromView) {
            fromView = [[UIView alloc] init];
            fromView = self.selectedViewController.view;

        }
        // Get the size of the view area.
        CGRect viewSize = fromView.frame;

        if (!toView) {
            toView = [[UIView alloc] init];
            toView = [[self.viewControllers objectAtIndex:targetVc] view];



            // Position it off screen.
            toView.frame = CGRectMake(swipeRatio, viewSize.origin.y, swipeRatio, viewSize.size.height);

            // Add the to view to the tab bar view.
            [fromView.superview addSubview:toView];
        }


        [UIView animateWithDuration:0 animations:^{
            // Animate the views on and off the screen. This will appear to slide.
            fromView.frame = CGRectMake(distance.x, viewSize.origin.y, swipeRatio, viewSize.size.height);
            toView.frame = CGRectMake(-swipeRatio+distance.x, viewSize.origin.y, swipeRatio, viewSize.size.height);

            toViewX = -swipeRatio+distance.x;
            fromViewX = distance.x;

        }];