the behavior of the UICollectionViewFlowLayout is not defined because:

the behavior of the UICollectionViewFlowLayout is not defined because:

 the item height must be less than the height of the UICollectionView minus the section insets top and bottom values, minus the content insets top and bottom values.

The relevant UICollectionViewFlowLayout instance is <UICollectionViewFlowLayout: 0x7fabf9580f60>, and it is attached to <UICollectionView: 0x7fabf9875800; frame = (0 0; 320 125); clipsToBounds = YES; autoresize = RM+BM; gestureRecognizers = <NSArray: 0x7fabf9573f70>; layer = <CALayer: 0x7fabf95769d0>; contentOffset: {0, 0}; contentSize: {0, 125}> collection view layout: <UICollectionViewFlowLayout: 0x7fabf9580f60>.

Make a symbolic breakpoint at UICollectionViewFlowLayoutBreakForInvalidSizes to catch this in the debugger.

- (void)viewDidLoad {
    [super viewDidLoad];

    
    self.automaticallyAdjustsScrollViewInsets = NO;
}

the behavior of the UICollectionViewFlowLayout is not defined because:

原文：http://www.cnblogs.com/levy/p/5203453.html