gistfile1.m

// Version 1
[[self.scrollView subviews] enumerateObjectsUsingBlock:^(UIView *obj, NSUInteger idx, BOOL *stop) {
  [UIView animateWithDuration:0.25 animations:^{
    obj.alpha = 0.0;
  } completion:^(BOOL finished) {
    [obj removeFromSuperview];
  }];
}];

// Version 2
NSArray *scrollSubviews = [self.scrollView subviews];
[UIView animateWithDuration:0.25 animations:^{
  [scrollSubviews enumerateObjectsUsingBlock:^(UIView *view, NSUInteger idx, BOOL *stop) {
    view.alpha = 0.0;
  }];
} completion:^(BOOL finished) {
  [scrollSubviews makeObjectsPerformSelector:@selector(removeFromSuperview)];
}];