title: AnimationGroup Crash
body: <p><strong>Demo：</strong></p>
  
  <pre><code>__block NSMutableArray *animaArr = [[NSMutableArray alloc] initWithCapacity:200];
  
  for ( int i = 3 ; i &gt; 0 ; i-- ) {
          CAKeyframeAnimation *anima1 = [CAKeyframeAnimation animationWithKeyPath:@"position"];
          NSValue *value0 = [NSValue valueWithCGPoint:CGPointMake(30,40)];
          NSValue *value1 = [NSValue valueWithCGPoint:CGPointMake(50,60)];
          anima1.values = [NSArray arrayWithObjects:value0,value1, nil];
          [animaArr addObject:anima1.values];
      }  
  
  CAAnimationGroup *groupAnimation = [CAAnimationGroup animation];
  groupAnimation.animations = animaArr;
  groupAnimation.duration = 5;
  [_movingChipImgView.layer addAnimation:groupAnimation forKey:nil];
  </code></pre>
  
  <p><strong>crash information:</strong></p>
  
  <blockquote>
    <p>2016-12-20 20:16:09.876 Pok[1781:474428] -[__NSArrayI setDefaultDuration:]: unrecognized selector sent to instance 0x60000022d9e0</p>
  </blockquote>