- (void)loadNextPage失败了。
断言失败 - [UICollectionView _endItemAnimationsWithInvalidationContext：tentativelyForReordering：animator：]
无法向第0部分插入行。或者到新的部分。 我每次调用api时都试图插入新的单元格。 json每页返回5个元素因此pagecount。
@interface feedCollection ()<UICollectionViewDelegate,UICollectionViewDataSource,UICollectionViewDelegateFlowLayout>
@property (weak, nonatomic) IBOutlet UICollectionView *collectionView;
@property (weak, nonatomic) IBOutlet UICollectionViewFlowLayout *flowLayout;
@property (nonatomic, assign) BOOL onlyImage;
@property (nonatomic, strong) NSMutableArray *feeds;
- (IBAction)addFeed:(id)sender;
- (IBAction)changeLayoutDirection:(id)sender;
@end
static const CGFloat kNewPageLoadScrollPercentageThreshold = 0.66;
@implementation feedCollection{
CGFloat screenWidth;
int pageNumber;
int sectionNum;
bool pageLoading;
}
- (void)viewDidLoad {
[super viewDidLoad];
pageNumber = 0;
sectionNum = 1;
CGRect screenRect = [[UIScreen mainScreen] bounds];
screenWidth = screenRect.size.width;
self.collectionView.delegate = self;
self.collectionView.dataSource = self;
// Do any additional setup after loading the view, typically from a nib.
self.feeds = [[NSMutableArray alloc]init];
}
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
[self fetchFeedApi];
}
static BOOL ShouldLoadNextPage(UICollectionView *collectionView)
{
CGFloat yOffset = collectionView.contentOffset.y;
CGFloat height = collectionView.contentSize.height - CGRectGetHeight(collectionView.frame);
return yOffset / height > kNewPageLoadScrollPercentageThreshold;
}
#pragma mark - flowlayout
-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
if(self.feeds.count > 0){
PostModel *feed = self.feeds[indexPath.row];
return [self.collectionView ar_sizeForCellWithIdentifier:@"DynamicHeightCell"
indexPath:indexPath
fixedWidth:screenWidth configuration:^(id cell) {
[cell filleCellWithFeed:feed];
}];
}
}
// Inside the implementation block:
#pragma mark - UICollectionViewDelegate
- (void)collectionView:(UICollectionView *)collectionView
didEndDisplayingCell:(UICollectionViewCell *)cell
forItemAtIndexPath:(NSIndexPath *)indexPath
{
[Helper showHUDWithStatus:@"Loading Next Page" blocking:YES];
BOOL shouldLoadNextPage = ShouldLoadNextPage(collectionView);
if (shouldLoadNextPage && !pageLoading) {
[self loadNextPage];
}
}
- (void)loadNextPage {
sectionNum = sectionNum + 1;
pageNumber = pageNumber + 1;
NSString* page = [NSString stringWithFormat:@"%d", pageNumber];
NSDictionary *params = [NSDictionary dictionaryWithObjectsAndKeys:page,@"page", nil];
[PruNSURLSession getUrl:API_GETFEED params:params success:^(NSData * _Nullable data, NSURLResponse * _Nullable response) {
NSError* error;
NSMutableArray* json = [NSJSONSerialization JSONObjectWithData:data
options:kNilOptions
error:&error];
if(!error){
for (NSDictionary * dict in json) {
NSError *error;
PostModel * post = [[PostModel alloc] initWithDictionary:dict error:&error];
if(!error){
[self.feeds addObject:post];
}
}
if(json.count >0){
NSLog(@"count : %lu",(unsigned long)self.feeds.count);
NSLog(@"sections : %d",sectionNum);
dispatch_async(dispatch_get_main_queue(), ^{
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:self.feeds.count-1 inSection:0];
[self.collectionView performBatchUpdates:^{
[self.collectionView deleteItemsAtIndexPaths:@[indexPath]];
[self.collectionView insertItemsAtIndexPaths:@[indexPath]];
} completion:^(BOOL finished) {
[Helper hideHUD];
}];
NSLog(@"%lu",(unsigned long)self.feeds.count);
});
}
}
else {
}
} failure:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
NSLog(@"%@",error);
}
];
}
#pragma mark - dataSources
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
NSLog(@"%d", sectionNum);
return 1;
}
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
if (self.feeds.count > 0 ){
return self.feeds.count;
}
return 0;
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
if(self.feeds.count > 0){
DynamicHeightCell *cell = [self.collectionView dequeueReusableCellWithReuseIdentifier:@"DynamicHeightCell" forIndexPath:indexPath];
PostModel *feed = self.feeds[indexPath.row];
[cell filleCellWithFeed:feed];
return cell;
}
return nil;
}
#pragma mark - funcs
- (void)fetchFeedApi {
NSString* page = [NSString stringWithFormat:@"%d", pageNumber];
NSDictionary *params = [NSDictionary dictionaryWithObjectsAndKeys:page,@"page", nil];
[MYNSURLSession getUrl:API_GETFEED params:params success:^(NSData * _Nullable data, NSURLResponse * _Nullable response) {
NSError* error;
NSMutableArray* json = [NSJSONSerialization JSONObjectWithData:data
options:kNilOptions
error:&error];
if(!error){
for (NSDictionary * dict in json) {
NSError *error;
PostModel * post = [[PostModel alloc] initWithDictionary:dict error:&error];
if(!error){
[self.feeds addObject:post];
}
}
if(json.count >0){
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
[self.collectionView reloadData];
}];
}
}
else {
}
} failure:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
NSLog(@"%@",error);
}
];
}
@end