swift – 使用setCollectionViewLayout导致崩溃,说找不到layoutAttributesForItemAtIndexPath

我有一个集合视图,我必须动态更改集合视图的布局.在设置新布局时,应用程序与日志崩溃,

2016-02-15 13：47：31.663 PhotoBoard [92347：5235792] ***断言失败 – [UICollectionViewData layoutAttributesForItemAtIndexPath：],/ buildroot / Library / People / com.apple.xbs / Source / UIKit_Sim / UIKit-3512.30. 14 / UICollectionViewData.m：666

2016-02-15 13：47：31.666 PhotoBoard [92347：5235792] *由于未捕获的异常’NSInternalInconsistencyException’而终止应用程序,原因：’没有UICollectionViewLayoutAttributes -layoutAttributesForItemAtIndexPath实例：{length = 2,path = 0 – 0}’
*第一次抛出调用堆栈：
(
0 CoreFoundation 0x000000010d94de65 __exceptionPreprocess 165
1 libobjc.A.dylib 0x000000010f8b5deb objc_exception_throw 48
2 CoreFoundation 0x000000010d94dcca [NSException raise：format：arguments：] 106
3基础0x000000010dfbe4de – [NSAssertionHandler handleFailureInMethod：object：file：lineNumber：description：] 198
4 UIKit 0x000000010ec4161c – [UICollectionViewData layoutAttributesForItemAtIndexPath：] 627
5 UIKit 0x000000010ebeee24 – [UICollectionView _setCollectionViewLayout：animated：isInteractive：completion：] 1606
6 UIKit 0x000000010ebee4db – [UICollectionView setCollectionViewLayout：] 318

在打印布局属性时,我看到一个布局属性项
layoutAttributesForItemAtIndexPath：{length = 2,path = 0 – 0}’,我在布局中看到一个条目,所以不确定为什么找不到布局属性,

属性索引路径：({length = 2,path = 0 – 0}); frame =(6 293; 298 403.695);

属性索引路径：({length = 2,path = 0 – 1}); frame =(6 293; 298 408.695);

属性索引路径：({length = 2,path = 0 – 2}); frame =(6 293; 298 418.695);

属性索引路径：({length = 2,path = 0 – 3}); frame =(6 293; 298 433.695);

属性索引路径：({length = 2,path = 0 – 4}); frame =(6 293; 298 453.695);

属性索引路径：({length = 2,path = 0 – 5}); frame =(6 293; 298 478.695);

属性索引路径：({length = 2,path = 0 – 6}); frame =(6 293; 298 508.695);

属性索引路径：({length = 2,path = 0 – 7}); frame =(6 293; 298 543.695);

属性索引路径：({length = 2,path = 0 – 8}); frame =(6 293; 298 583.695);

属性索引路径：({length = 2,path = 0 – 9}); frame =(6 293; 298 628.695);

属性索引路径：({length = 2,path = 0 – 10}); frame =(6 293; 298 678.695);

属性索引路径：({length = 2,path = 0 – 11}); frame =(6 293; 298 733.695);

属性索引路径：({length = 2,path = 0 – 12}); frame =(6 293; 298 793.695);

属性索引路径：({length = 2,path = 0 – 13}); frame =(6 293; 298 858.695);

属性索引路径：({length = 2,path = 0 – 14}); frame =(6 293; 298 928.695);

属性索引路径：({length = 2,path = 0 – 15}); frame =(6 293; 298 1003.69);

这就是我设置新自定义布局的方式,

self.collectionView!.collectionViewLayout = self.stackLayout
        self.stackLayout.delegate = self
        self.collectionView!.collectionViewLayout.invalidateLayout()
        self.collectionView!.setCollectionViewLayout(self.stackLayout,animated:true)
        self.collectionView?.reloadData()

如果我静态加载两个自定义布局它们工作正常,只有在动态更改布局时才会发生崩溃.

我有同样的问题,这解决了我的问题.

如果要使用多个自定义布局进行切换,则在两个自定义布局类中重写以下方法,

- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
 - (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath

Swift示例：

override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
    return cache[indexPath.item]
}

目标C的示例：

- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
{ 
   return self.cache[indexPath.item];
}

快乐编码..！