iOS9下UICollectionViewCell的awakeFromNib問題

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　　最近項目測試出一個隱藏已久的bug，經過多番測試，發現在iOS9下自訂的一個UICollectionViewCell只走一次awakeFromNib。

　　具體情況是，項目中有一個控制器用到了自訂的UICollectionView，有四組資料，然而有三組自訂的UICollectionViewCell布局和子控制項是一樣的，所以只註冊了兩種類型的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 YimaiDoctorGroupMoreTopicCollectionViewstatic 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 = 0;    layout.minimumInteritemSpacing = 0;            //初始化    YimaiDoctorGroupMoreTopicCollectionView *collection = [[YimaiDoctorGroupMoreTopicCollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];    //註冊　　 [collection registerNib:[UINib nibWithNibName:kCommonIdentifier bundle:nil] forCellWithReuseIdentifier:kCommonIdentifier];    [collection registerNib:[UINib nibWithNibName:kMyIdentifier bundle:nil] forCellWithReuseIdentifier:kMyIdentifier];    //分頁    collection.pagingEnabled = YES;    //資料來源，代理    collection.delegate = object;    collection.dataSource = object;    //    collection.backgroundColor = [UIColor clearColor];    return collection;}@end

在所屬控制器的資料來源方法中，初始化和賦值

#pragma mark - UICollectionViewDelegate- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{    return 4;}- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{    static NSString *identifier;    if (indexPath.item < 3) {        identifier = @"YimaiDoctorGroupMoreTopicCommonCollectionCell";        YimaiDoctorGroupMoreTopicCommonCollectionCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];        cell.type = [NSString stringWithFormat:@"%ld",indexPath.item + 1];        FLOG(@"cell ======== %@", cell);        return cell;    }else{        identifier = @"YimaiDoctorGroupMoreTopicMyCollectionCell";        YimaiDoctorGroupMoreTopicMyCollectionCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];        cell.type = (int)indexPath.item + 1;        return cell;    }}

每個自訂的UICollectionViewCell裡面添加了UITableView作為子控制項，並且能上拉載入，下拉重新整理，所以有一些初始化

#pragma mark - life cycle- (void)awakeFromNib {    [super awakeFromNib];    //設定tableview    [self setTableViewAttributes];    self.page = 1;}

當前控制器裡頂部還加了資格按鈕，用來點擊可以實現UICollectionView的滑動

上面是核心源碼，看似很正確的實現，最後卻驗證在iOS9下“不能滑動”，即看似下面這句話不執行

[self.collectionView setContentOffset:CGPointMake(index * kScreenW, 0) animated:NO];

最後通過各種系統版本機型的調試，驗證了，上面的這句setContentOffset沒有問題，有問題的是，iOS9上YimaiDoctorGroupMoreTopicCommonCollectionCell的awakeFromNib方法只執行了一次，而在其他的手機版本下走了三次，所以導致當初註冊的兩種類型的cell，這裡三種看似相同的cell現在都是完全一樣了，資料都一樣。類似於是用的同一個地址，而不是我們認為的，三種長得一樣的cell都擁有自己獨立的地址，所以才導致看著是沒滑動，具體為什麼還在不同的系統版本上有這種情況，查了資料也沒什麼頭緒，有瞭解的夥伴們還請多多指點！！最後只附上解決方案：三種看似相同的cell不複用了，於是有了下面重用標識符的修改

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{    static NSString *identifier;    if (indexPath.item < 3) {        identifier = [NSString stringWithFormat:@"%@-%ld",@"YimaiDoctorGroupMoreTopicCommonCollectionCell", indexPath.item];        YimaiDoctorGroupMoreTopicCommonCollectionCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];        cell.type = [NSString stringWithFormat:@"%ld",indexPath.item + 1];        FLOG(@"cell ======== %@", cell);        return cell;    }else{        identifier = @"YimaiDoctorGroupMoreTopicMyCollectionCell";        YimaiDoctorGroupMoreTopicMyCollectionCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];        cell.type = (int)indexPath.item + 1;        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 = 0;    layout.minimumInteritemSpacing = 0;            //初始化    YimaiDoctorGroupMoreTopicCollectionView *collection = [[YimaiDoctorGroupMoreTopicCollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:layout];    //註冊    //解決ios9下 自訂的一個UICollectionViewCell只走一次awakeFromNib    for (int i = 0; i < 3; 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];    //分頁    collection.pagingEnabled = YES;    //資料來源，代理    collection.delegate = object;    collection.dataSource = object;    //    collection.backgroundColor = [UIColor clearColor];    return collection;}

 

iOS9下UICollectionViewCell的awakeFromNib問題