iOS9下UICollectionViewCell的awakeFromNib问题

时间:2021-01-31 16:37:03

  最近项目测试出一个隐藏已久的bug,经过多番测试,发现在iOS9下自定义的一个UICollectionViewCell只走一次awakeFromNib。

  具体情况是,项目中有一个控制器用到了自定义的UICollectionView,有四组数据,然而有三组自定义的UICollectionViewCell布局和子控件是一样的,所以只注册了两种类型的cell

#import <UIKit/UIKit.h>

@interface YimaiDoctorGroupMoreTopicCollectionView : UICollectionView

+ (instancetype)collectionViewWithObject:(id)object;

@end
#define kCollectionviewHeight 96.0
#define kCommonIdentifier @"YimaiDoctorGroupMoreTopicCommonCollectionCell"
#define kMyIdentifier @"YimaiDoctorGroupMoreTopicMyCollectionCell"
#import "YimaiDoctorGroupMoreTopicCollectionView.h" @implementation YimaiDoctorGroupMoreTopicCollectionView
static NSString const *commonIdentifier = @"YimaiDoctorGroupMoreTopicCommonCollectionCell";
static NSString const *myIdentifier = @"YimaiDoctorGroupMoreTopicMyCollectionCell"; + (instancetype)collectionViewWithObject:(id)object
{
//流水布局
UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
CGFloat itemHeight = kScreenH - kCollectionviewHeight - kNavigtaionHeight;
layout.itemSize = CGSizeMake(kScreenW, itemHeight);
layout.minimumLineSpacing = ;
layout.minimumInteritemSpacing = ; //初始化
YimaiDoctorGroupMoreTopicCollectionView *collection = [[YimaiDoctorGroupMoreTopicCollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
//注册
   [collection registerNib:[UINib nibWithNibName:kCommonIdentifier bundle:nil] forCellWithReuseIdentifier:kCommonIdentifier];
[collection registerNib:[UINib nibWithNibName:kMyIdentifier bundle:nil] forCellWithReuseIdentifier:kMyIdentifier];
//分页
collection.pagingEnabled = YES;
//数据源,代理
collection.delegate = object;
collection.dataSource = object;
//
collection.backgroundColor = [UIColor clearColor];
return collection;
} @end

在所属控制器的数据源方法中,初始化和赋值

#pragma mark - UICollectionViewDelegate
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return ;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *identifier;
if (indexPath.item < ) {
identifier = @"YimaiDoctorGroupMoreTopicCommonCollectionCell";
YimaiDoctorGroupMoreTopicCommonCollectionCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
cell.type = [NSString stringWithFormat:@"%ld",indexPath.item + ];
FLOG(@"cell ======== %@", cell);
return cell;
}else{
identifier = @"YimaiDoctorGroupMoreTopicMyCollectionCell";
YimaiDoctorGroupMoreTopicMyCollectionCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
cell.type = (int)indexPath.item + ;
return cell;
}
}

每个自定义的UICollectionViewCell里面添加了UITableView作为子控件,并且能上拉加载,下拉刷新,所以有一些初始化

#pragma mark - life cycle
- (void)awakeFromNib {
[super awakeFromNib];
//设置tableview
[self setTableViewAttributes];
self.page = ;
}

当前控制器里顶部还加了资格按钮,用来点击可以实现UICollectionView的滑动

上面是核心源码,看似很正确的实现,最后却验证在iOS9下“不能滑动”,即看似下面这句话不执行

[self.collectionView setContentOffset:CGPointMake(index * kScreenW, ) animated:NO];

最后通过各种系统版本机型的调试,验证了,上面的这句setContentOffset没有问题,有问题的是,iOS9上YimaiDoctorGroupMoreTopicCommonCollectionCell的awakeFromNib方法只执行了一次,而在其他的手机版本下走了三次,所以导致当初注册的两种类型的cell,这里三种看似相同的cell现在都是完全一样了,数据都一样。类似于是用的同一个地址,而不是我们认为的,三种长得一样的cell都拥有自己独立的地址,所以才导致看着是没滑动,具体为什么还在不同的系统版本上有这种情况,查了资料也没什么头绪,有了解的伙伴们还请多多指点!!最后只附上解决方法:三种看似相同的cell不复用了,于是有了下面重用标识符的修改

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *identifier;
if (indexPath.item < ) {
identifier = [NSString stringWithFormat:@"%@-%ld",@"YimaiDoctorGroupMoreTopicCommonCollectionCell", indexPath.item];
YimaiDoctorGroupMoreTopicCommonCollectionCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
cell.type = [NSString stringWithFormat:@"%ld",indexPath.item + ];
FLOG(@"cell ======== %@", cell);
return cell;
}else{
identifier = @"YimaiDoctorGroupMoreTopicMyCollectionCell";
YimaiDoctorGroupMoreTopicMyCollectionCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
cell.type = (int)indexPath.item + ;
return cell;
}
}
+ (instancetype)collectionViewWithObject:(id)object
{
//流水布局
UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
CGFloat itemHeight = kScreenH - kCollectionviewHeight - kNavigtaionHeight;
layout.itemSize = CGSizeMake(kScreenW, itemHeight);
layout.minimumLineSpacing = ;
layout.minimumInteritemSpacing = ; //初始化
YimaiDoctorGroupMoreTopicCollectionView *collection = [[YimaiDoctorGroupMoreTopicCollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];
//注册
//解决ios9下 自定义的一个UICollectionViewCell只走一次awakeFromNib
for (int i = ; i < ; i++) {
[collection registerNib:[UINib nibWithNibName:kCommonIdentifier bundle:nil] forCellWithReuseIdentifier:[NSString stringWithFormat:@"%@-%d", @"YimaiDoctorGroupMoreTopicCommonCollectionCell", i]];
}
// [collection registerNib:[UINib nibWithNibName:kCommonIdentifier bundle:nil] forCellWithReuseIdentifier:kCommonIdentifier];
[collection registerNib:[UINib nibWithNibName:kMyIdentifier bundle:nil] forCellWithReuseIdentifier:kMyIdentifier];
//分页
collection.pagingEnabled = YES;
//数据源,代理
collection.delegate = object;
collection.dataSource = object;
//
collection.backgroundColor = [UIColor clearColor];
return collection;
}