ios 如何设置 UICollectionViewDelegateFlowLayout？
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How to set UICollectionViewDelegateFlowLayout?
提问by Rich Apodaca
A UIViewController maintains a reference to a UICollectionView. The controller should modify the built-in flow layout using the UICollectionViewDelegateFlowLayout.
UIViewController 维护对 UICollectionView 的引用。控制器应该使用 UICollectionViewDelegateFlowLayout 修改内置流布局。
It's pretty easy to set the view's data source to self:
将视图的数据源设置为 self 非常容易：
MyViewController.m
视图控制器.m
- (void)viewDidLoad
{
self.collectionView.dataSource = self;
}
But how do I set the controller to be the delegate flow layout of the view?
但是如何将控制器设置为视图的委托流布局？
- (void)viewDidLoad
{
self.collectionView.dataSource= self;
// self.collectionView.??? = self;
}
I've tried:
我试过了：
- (void)viewDidLoad
{
self.collectionView.dataSource= self;
self.collectionView.collectionViewLayout = self;
}
But I get the error: "Incompatible pointer types assigning ...".
但我收到错误：“不兼容的指针类型分配......”。
The collection header file looks like this:
集合头文件如下所示：
MyViewController.h
视图控制器.h
@interface MyViewController : UIViewController <UICollectionViewDataSource, UICollectionViewDelegateFlowLayout>
回答by John Estropia
Just self.collectionView.delegate = self;. Note that UICollectionViewDelegateFlowLayoutinherits from UICollectionViewDelegate.
只是self.collectionView.delegate = self;。请注意，UICollectionViewDelegateFlowLayout继承自UICollectionViewDelegate.
I admit it can catch you off guard at first.
我承认它一开始会让你措手不及。
Oh and this will only work if self.collectionView.collectionViewLayoutis actually set to your flow layout. (or set with initWithFrame:collectionViewLayout:)
哦，这只有在self.collectionView.collectionViewLayout实际设置为您的流程布局时才有效。（或设置为initWithFrame:collectionViewLayout:）
回答by WINSergey
According to previous answer just example of use. It really not clear but I can show how it works:
根据之前的回答只是使用示例。这真的不清楚，但我可以展示它是如何工作的：
@interface PrettyViewController()<UICollectionViewDelegateFlowLayout, UICollectionViewDataSource>
//some code
@end
@implementation PrettyViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.collectionView.delegate = self;//bingo! right here
}
#pragma mark - UICollectionViewDelegateFlowLayout
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section {
return CGSizeMake([[UIScreen mainScreen] bounds].size.width, 20.0);
}
@end
回答by ingconti
my two cents for OSX mojave - Swift
我的OSX mojave两分钱- Swift
(I've fallen here searching for NSCollectionView... I do know question was about UICollectionView..)
（我在这里寻找 NSCollectionView ......我知道问题是关于 UICollectionView ......）
All said above (specifying delegate implies cell size, too) is correct for OSX, too.
上面所说的（指定委托也意味着单元格大小）对于 OSX 也是正确的。
NOTEif You write:
注意如果你写：
class MyViewController: NSCollectionViewDelegate, NSCollectionViewDataSource, NSCollectionViewDelegateFlowLayout{
类 MyViewController：NSCollectionViewDelegate、NSCollectionViewDataSource、 NSCollectionViewDelegateFlowLayout{
the method:
方法：
func collectionView(_ collectionView: NSCollectionView, layout collectionViewLayout: NSCollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> NSSize
func collectionView(_ collectionView: NSCollectionView, layout collectionViewLayout: NSCollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> NSSize
willbe called.
将被调用。
IF removed, no delegate method will be called. (as class does not obey to the protocol).
如果删除，则不会调用任何委托方法。（因为班级不遵守协议）。
