Definindo um novo collectionViewLayout para o UICollectionView fornecendo tela em branco
Estou começando a experimentar layouts UICollectionView personalizados. Eu tenho um UICollectionView no meu UIViewController que está em conformidade com os protocolos UICollectionViewDataSource e UICollectionViewFlowLayout. Cada célula é apenas uma imagem e um rótulo. Eu tenho um botão que faz isso:
- (IBAction)switchLayout:(id)sender {
PinchLayout *pinchLayout = [[PinchLayout alloc] init];
[self.collectionView setCollectionViewLayout:pinchLayout];
}
O PinchLayout é copiado diretamente do código de amostra da Apple. Quando o método switchLayout: é chamado, meu collectionView desaparece. Eu não entendo porque. Eu pensei que iria animar as novas posições. Ou neste caso, não faça nada além de adicionar suporte a gestos para o novo layout. Então, quando eu aperto o botão novamente, vejo um novo layout em que todas as células da minha coleção são reduzidas em versões do tamanho original. Aqui está o PinchLayout.m
-(void)applyPinchToLayoutAttributes:(UICollectionViewLayoutAttributes*)layoutAttributes
{
if ([layoutAttributes.indexPath isEqual:self.pinchedCellPath])
{
layoutAttributes.transform3D = CATransform3DMakeScale(self.pinchedCellScale, self.pinchedCellScale, 1.0);
layoutAttributes.center = self.pinchedCellCenter;
layoutAttributes.zIndex = 1;
}
}
-(NSArray*)layoutAttributesForElementsInRect:(CGRect)rect
{
NSArray* allAttributesInRect = [super layoutAttributesForElementsInRect:rect];
for (UICollectionViewLayoutAttributes* cellAttributes in allAttributesInRect)
{
[self applyPinchToLayoutAttributes:cellAttributes];
}
return allAttributesInRect;
}
-(UICollectionViewLayoutAttributes*)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewLayoutAttributes* attributes = [super layoutAttributesForItemAtIndexPath:indexPath];
[self applyPinchToLayoutAttributes:attributes];
return attributes;
}
-(void)setPinchedCellScale:(CGFloat)scale
{
_pinchedCellScale = scale;
[self invalidateLayout];
}
- (void)setPinchedCellCenter:(CGPoint)origin {
_pinchedCellCenter = origin;
[self invalidateLayout];
}
Alguma ideia? Obrigado!
Edit: Se eu mudar o método de ação para
- (IBAction)switchLayout:(id)sender {
PinchLayout *pinchLayout = [[PinchLayout alloc] init];
[self.collectionView setCollectionViewLayout:pinchLayout animated:YES];
}
Eu vejo todas as células da minha coleção saindo da tela para o topo. Não sei por que eles fazem isso.
Edit 2: eu registrei os atributos e cellAttributes e parece que os quadros estão sempre nos limites da tela, então eu ainda não tenho certeza porque as células vão fora da tela para o topo. Aqui está o log:
2012-12-04 21:54:40.808 Animations[2079:c07] attributes: <UICollectionViewLayoutAttributes: 0x7516450> index path: (<NSIndexPath 0xe111180> 2 indexes [0, 4]); frame = (297.2 100; 50 50);
2012-12-04 21:54:40.809 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7611df0> index path: (<NSIndexPath 0x76236e0> 2 indexes [0, 0]); frame = (50 100; 50 50);
2012-12-04 21:54:40.812 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x76235e0> index path: (<NSIndexPath 0x7623700> 2 indexes [0, 1]); frame = (111.8 100; 50 50);
2012-12-04 21:54:40.812 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x76263c0> index path: (<NSIndexPath 0x76263a0> 2 indexes [0, 2]); frame = (173.6 100; 50 50);
2012-12-04 21:54:40.813 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7623910> index path: (<NSIndexPath 0x7626440> 2 indexes [0, 3]); frame = (235.4 100; 50 50);
2012-12-04 21:54:40.813 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x76239a0> index path: (<NSIndexPath 0x7626460> 2 indexes [0, 4]); frame = (297.2 100; 50 50);
2012-12-04 21:54:40.813 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7623ff0> index path: (<NSIndexPath 0x7623a40> 2 indexes [0, 5]); frame = (359 100; 50 50);
2012-12-04 21:54:40.814 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x76240a0> index path: (<NSIndexPath 0x7624070> 2 indexes [0, 6]); frame = (420.8 100; 50 50);
2012-12-04 21:54:40.853 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7624150> index path: (<NSIndexPath 0x7624120> 2 indexes [0, 7]); frame = (482.6 100; 50 50);
2012-12-04 21:54:40.853 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7624200> index path: (<NSIndexPath 0x76241d0> 2 indexes [0, 8]); frame = (544.4 100; 50 50);
2012-12-04 21:54:40.853 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x76242d0> index path: (<NSIndexPath 0x7623a20> 2 indexes [0, 9]); frame = (606.2 100; 50 50);
2012-12-04 21:54:40.854 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7624380> index path: (<NSIndexPath 0x7624350> 2 indexes [0, 10]); frame = (668 100; 50 50);
2012-12-04 21:54:40.854 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7624430> index path: (<NSIndexPath 0x7624400> 2 indexes [0, 11]); frame = (729.8 100; 50 50);
2012-12-04 21:54:40.854 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x76244e0> index path: (<NSIndexPath 0x76244b0> 2 indexes [0, 11]); frame = (50 160; 50 50);
2012-12-04 21:54:40.855 Animations[2079:c07] attributes: <UICollectionViewLayoutAttributes: 0x76427e0> index path: (<NSIndexPath 0xe1112f0> 2 indexes [0, 6]); frame = (420.8 100; 50 50);
2012-12-04 21:54:40.855 Animations[2079:c07] attributes: <UICollectionViewLayoutAttributes: 0x7517f80> index path: (<NSIndexPath 0xe1113a0> 2 indexes [0, 7]); frame = (482.6 100; 50 50);
2012-12-04 21:54:40.855 Animations[2079:c07] attributes: <UICollectionViewLayoutAttributes: 0x7149030> index path: (<NSIndexPath 0xe111450> 2 indexes [0, 8]); frame = (544.4 100; 50 50);
2012-12-04 21:54:40.855 Animations[2079:c07] attributes: <UICollectionViewLayoutAttributes: 0x7149210> index path: (<NSIndexPath 0xe111230> 2 indexes [0, 9]); frame = (606.2 100; 50 50);
2012-12-04 21:54:40.856 Animations[2079:c07] attributes: <UICollectionViewLayoutAttributes: 0x7518220> index path: (<NSIndexPath 0xe111020> 2 indexes [0, 2]); frame = (173.6 100; 50 50);
2012-12-04 21:54:40.856 Animations[2079:c07] attributes: <UICollectionViewLayoutAttributes: 0x7518510> index path: (<NSIndexPath 0xe1110d0> 2 indexes [0, 3]); frame = (235.4 100; 50 50);
2012-12-04 21:54:40.856 Animations[2079:c07] attributes: <UICollectionViewLayoutAttributes: 0x7518760> index path: (<NSIndexPath 0xe111180> 2 indexes [0, 4]); frame = (297.2 100; 50 50);
2012-12-04 21:54:40.856 Animations[2079:c07] attributes: <UICollectionViewLayoutAttributes: 0x7518ac0> index path: (<NSIndexPath 0xe111250> 2 indexes [0, 5]); frame = (359 100; 50 50);
2012-12-04 21:54:40.857 Animations[2079:c07] attributes: <UICollectionViewLayoutAttributes: 0x7642bf0> index path: (<NSIndexPath 0xe110e00> 2 indexes [0, 0]); frame = (50 100; 50 50);
2012-12-04 21:54:40.857 Animations[2079:c07] attributes: <UICollectionViewLayoutAttributes: 0x7518d40> index path: (<NSIndexPath 0xe110f80> 2 indexes [0, 1]); frame = (111.8 100; 50 50);
2012-12-04 21:54:40.857 Animations[2079:c07] attributes: <UICollectionViewLayoutAttributes: 0xe111600> index path: (<NSIndexPath 0xe1115d0> 2 indexes [0, 10]); frame = (668 100; 50 50);
2012-12-04 21:54:40.858 Animations[2079:c07] attributes: <UICollectionViewLayoutAttributes: 0x7642dd0> index path: (<NSIndexPath 0xe111680> 2 indexes [0, 11]); frame = (50 160; 50 50);
2012-12-04 21:54:41.161 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x76240a0> index path: (<NSIndexPath 0x7643bf0> 2 indexes [0, 0]); frame = (50 100; 50 50);
2012-12-04 21:54:41.162 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7623ff0> index path: (<NSIndexPath 0x7644e90> 2 indexes [0, 1]); frame = (111.8 100; 50 50);
2012-12-04 21:54:41.162 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x76239a0> index path: (<NSIndexPath 0x7645310> 2 indexes [0, 2]); frame = (173.6 100; 50 50);
2012-12-04 21:54:41.162 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7623910> index path: (<NSIndexPath 0x7642bb0> 2 indexes [0, 3]); frame = (235.4 100; 50 50);
2012-12-04 21:54:41.163 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x76263c0> index path: (<NSIndexPath 0x761ab30> 2 indexes [0, 4]); frame = (297.2 100; 50 50);
2012-12-04 21:54:41.163 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x76235e0> index path: (<NSIndexPath 0x7642170> 2 indexes [0, 5]); frame = (359 100; 50 50);
2012-12-04 21:54:41.163 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7611df0> index path: (<NSIndexPath 0x7642190> 2 indexes [0, 6]); frame = (420.8 100; 50 50);
2012-12-04 21:54:41.163 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7642070> index path: (<NSIndexPath 0x7642230> 2 indexes [0, 7]); frame = (482.6 100; 50 50);
2012-12-04 21:54:41.164 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7642ea0> index path: (<NSIndexPath 0x76422f0> 2 indexes [0, 8]); frame = (544.4 100; 50 50);
2012-12-04 21:54:41.164 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7645d00> index path: (<NSIndexPath 0x7641d30> 2 indexes [0, 9]); frame = (606.2 100; 50 50);
2012-12-04 21:54:41.164 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x76469b0> index path: (<NSIndexPath 0x7642470> 2 indexes [0, 10]); frame = (668 100; 50 50);
2012-12-04 21:54:41.164 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7646cb0> index path: (<NSIndexPath 0x7642490> 2 indexes [0, 11]); frame = (729.8 100; 50 50);
2012-12-04 21:54:41.165 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x76470b0> index path: (<NSIndexPath 0x7646d30> 2 indexes [0, 11]); frame = (50 160; 50 50);
2012-12-04 21:54:41.165 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7517e40> index path: (<NSIndexPath 0x7517e10> 2 indexes [0, 0]); frame = (50 100; 50 50);
2012-12-04 21:54:41.165 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7517f00> index path: (<NSIndexPath 0x7517ed0> 2 indexes [0, 1]); frame = (111.8 100; 50 50);
2012-12-04 21:54:41.166 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7517fb0> index path: (<NSIndexPath 0x7517f80> 2 indexes [0, 2]); frame = (173.6 100; 50 50);
2012-12-04 21:54:41.166 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7518060> index path: (<NSIndexPath 0x7518030> 2 indexes [0, 3]); frame = (235.4 100; 50 50);
2012-12-04 21:54:41.166 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7518110> index path: (<NSIndexPath 0x75180e0> 2 indexes [0, 4]); frame = (297.2 100; 50 50);
2012-12-04 21:54:41.166 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x75181d0> index path: (<NSIndexPath 0x75181b0> 2 indexes [0, 5]); frame = (359 100; 50 50);
2012-12-04 21:54:41.167 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7518280> index path: (<NSIndexPath 0x7518250> 2 indexes [0, 6]); frame = (420.8 100; 50 50);
2012-12-04 21:54:41.167 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7518330> index path: (<NSIndexPath 0x7518300> 2 indexes [0, 7]); frame = (482.6 100; 50 50);
2012-12-04 21:54:41.167 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x75183e0> index path: (<NSIndexPath 0x75183b0> 2 indexes [0, 8]); frame = (544.4 100; 50 50);
2012-12-04 21:54:41.167 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x75184b0> index path: (<NSIndexPath 0x7518190> 2 indexes [0, 9]); frame = (606.2 100; 50 50);
2012-12-04 21:54:41.168 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7518560> index path: (<NSIndexPath 0x7518530> 2 indexes [0, 10]); frame = (668 100; 50 50);
2012-12-04 21:54:41.168 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x7518610> index path: (<NSIndexPath 0x75185e0> 2 indexes [0, 11]); frame = (729.8 100; 50 50);
2012-12-04 21:54:41.168 Animations[2079:c07] cellAttributes: <UICollectionViewLayoutAttributes: 0x75186c0> index path: (<NSIndexPath 0x7518690> 2 indexes [0, 11]); frame = (50 160; 50 50);