拖动视图在iOS7中有效，在iOS8中，每次都会将视图重置为左上角

Question

I have a view called progressView that I have made draggable like this:

-(void)viewDidLoad

...
    self.panGesture = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(handlePanGesture:)];
    [self.progressView addGestureRecognizer:self.panGesture];
...


-(void) displayPollingFor:(double)numOfSeconds
{
    self.progressView.hidden = NO;
    self.pollTimeLeftLabel.textColor = [UIColor whiteColor];

    [self.view insertSubview:self.progressView aboveSubview:self.moviePlayer.view];
    self.progressView.center = CGPointMake(self.view.frame.size.width - self.progressView.frame.size.width / 2 - 10, self.moviePlayer.view.frame.size.height / 2);
    self.progressView.accessibilityElementsHidden = YES;
    self.progressView.translatesAutoresizingMaskIntoConstraints = false;

    [UIView animateWithDuration:4 animations:^{
        self.progressView.alpha = .8;
        self.progressView.hidden = NO;
    }];

    self.progressView.thicknessRatio = 0.2;
    self.progressView.textColor = [UIColor blueColor];

    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(touchPollBtn:)];
    //    tap.cancelsTouchesInView = NO;
    [self.progressView addGestureRecognizer:tap];


    self.pollEndsLabel.hidden = NO;
    self.minsSecsLabel.hidden = NO;

    timer = [NSTimer scheduledTimerWithTimeInterval:1.0
                                             target:self
                                           selector:@selector(updateLabel:)
                                           userInfo:nil
                                            repeats:YES ];

    pollTimeLeft = pollTimeTotal = numOfSeconds;
    [self updateLabel:nil];
}

-(void)handlePanGesture:(UIGestureRecognizer*)gesture
{
    self.progressView.center = [gesture locationInView:self.view];

    if (self.progressView.center.y > 100) {
        self.progressView.center = CGPointMake([gesture locationInView:self.view].x, 100);
    }
    else if (self.progressView.center.y < 30) {
        self.progressView.center = CGPointMake([gesture locationInView:self.view].x, 40);
    }
}

This works fine in iOS7 and I can drag it and it will stay where I left it. in iOS8 the view always returns to the top left corner of the view. How can I fix this?

Thanks

Answer 1

self.progressView.translatesAutoresizingMaskIntoConstraints = true;

fixes this for iOS8. I don't know what changed between iOS7 and iOS8 to make this an issue though, so I'd be happy to have someone explain it still.