Why UIKit Dynamics doesn`t work?
ios, uikit-dynamics
Solution
Your `UIDynamicAnimator` is deallocated when `viewDidLoad` returns. It can't animate anything if it's deallocated. Make a property:
@property (nonatomic) UIDynamicAnimator *animator;
And set it:
self.animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view];
Problem
I am studying iOS development now. When I add a rect view and want it be effected by the gravity, build and run my test app, I find it does`t have the gravity. This is the viewDidLoad code in my viewController.m : ``` [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. UIView *squre = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 100, 100)]; squre.backgroundColor = [UIColor grayColor]; [self.view addSubview:squre]; UIDynamicAnimator *_animator = [[UIDynamicAnimator alloc] initWithReferenceView:self.view]; UIGravityBehavior *_gravity = [[UIGravityBehavior alloc] initWithItems:@[squre]]; [_animator addBehavior:_gravity]; ```