UITableView重复Firebase数据 [英] UITableView repeating Firebase Data

问题描述

我正在重复Firebase的内容，而我似乎无法弄清楚我做错了什么。在firebase我有6个职位。 tableview是填充6个单元格，但所有6个单元格具有相同的数据，其他5个职位不在那里。

   - （UITableViewCell *）tableView：（UITableView *）tableView cellForRowAtIndexPath：（NSIndexPath *）indexPath 
 
 {
 RankingsCell * cell = [tableView dequeueReusableCellWithIdentifier：@RankingsCell]; 
 self.ref = [[FIRDatabase database] reference]; 
 posts = [ref child：@posts]; 
 $ b $ posts $（b 
 $ snapshot $ snapshot $ $ 
 
 
 
 
 
 
 
 
 
 NSString * username = snapshot.value [@Name]; 
 NSString * date = snapshot.value [@Date]; 
 NSString * combatPower = snapshot.value [@Combat Power]; 
 NSString * pokemon = snapshot.value [@Pokemon]; 
 NSString * pokemonURL = snapshot.value [@Pokemon Image]; 
 NSString * picURL = snapshot.value [@Profile Picture]; 
 int CP = [combatPower intValue]; 
 
 cell.usernameOutlet.text = username; 
 cell.dateOutlet.text = date; 
 cell.combatPowerLabel.text = [NSString stringWithFormat：@COMBAT POWER：％d，CP]; 
 cell.pokemonLabel.text = pokemon; 
 [cell downloadUserImage：picURL]; 
 [cell downloadPokemonImage：pokemonURL]; 
 
 
 withCancelBlock：^（NSError * _Nonnull error）
 {
 NSLog（@％@，error.localizedDescription）; 
}]; 
返回单元格; 
 
 $ / code> 




解决方案

cellForRowAtIndex：方法被称为每个单元，所以你不应该在那里做你的数据库工作，它只是负责一次创建一个单元格。 b
$ b

因此，在 viewDidLoad：或<$ c中调用 observeEventType：
$ b

   - （void）viewDidLoad 
 {$ b> viewDidAppear： $ b [super viewDidLoad]; 
 
 self.ref = [[FIRDatabase database] reference]; 
 posts = [ref child：@posts]; 
 
 [posts observeEventType：FIRDataEventTypeValue withBlock：^（FIRDataSnapshot * snapshot）
 {
 self.allSnapshots = [NSMutableArray array]; 
 
（snapshot.children中的快照）
 {
 [self.allSnapshots addObject：snapshot]; 
} 
 
 [self.tableView reloadData]; //获取数据后刷新表视图
} // ..错误... 
} 
  

并在 numberOfRowsForInSection：

   - （NSInteger） tableView：（UITableView *）tableView numberOfRowsInSection：（NSInteger）section 
 {
 return [self.allSnapshots count]; 
 
 $ / code> 

在 cellForRowAtIndex： {$（$ {$ p
$ b $ pre
RankingsCell * cell = [tableView dequeueReusableCellWithIdentifier：@RankingsCell];

FIRDataSnapshot * snapshot = [self.allSnapshots objectAtIndex：indexPath.row];

NSString * username = snapshot.value [@Name];
NSString * date = snapshot.value [@Date];
NSString * combatPower = snapshot.value [@Combat Power];
NSString * pokemon = snapshot.value [@Pokemon];
NSString * pokemonURL = snapshot.value [@Pokemon Image];
NSString * picURL = snapshot.value [@Profile Picture];
int CP = [combatPower intValue];

cell.usernameOutlet.text = username;
cell.dateOutlet.text = date;
cell.combatPowerLabel.text = [NSString stringWithFormat：@COMBAT POWER：％d，CP];
cell.pokemonLabel.text = pokemon;
[cell downloadUserImage：picURL];
[cell downloadPokemonImage：pokemonURL];

return cell;
}


I'm getting repeated content from Firebase, and I can't seem to figure out what I am doing wrong. In firebase I have 6 posts. The tableview is populating 6 cells, but all 6 cells have the same data, and the 5 other posts are not there.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath

{
    RankingsCell *cell = [tableView dequeueReusableCellWithIdentifier:@"RankingsCell"];
    self.ref = [[FIRDatabase database] reference];
    posts = [ref child:@"posts"];

    [posts observeEventType:FIRDataEventTypeValue withBlock:^(FIRDataSnapshot *snapshot)
     {
         for (snapshot in snapshot.children)
         {
             NSString *username = snapshot.value[@"Name"];
             NSString *date = snapshot.value[@"Date"];
             NSString *combatPower = snapshot.value[@"Combat Power"];
             NSString *pokemon = snapshot.value[@"Pokemon"];
             NSString *pokemonURL = snapshot.value[@"Pokemon Image"];
             NSString *picURL = snapshot.value[@"Profile Picture"];
             int CP = [combatPower intValue];

             cell.usernameOutlet.text = username;
             cell.dateOutlet.text = date;
             cell.combatPowerLabel.text = [NSString stringWithFormat:@"COMBAT POWER: %d", CP];
             cell.pokemonLabel.text = pokemon;
             [cell downloadUserImage:picURL];
             [cell downloadPokemonImage:pokemonURL];
         }
     }
        withCancelBlock:^(NSError * _Nonnull error)
     {
         NSLog(@"%@", error.localizedDescription);
     }];
    return cell;
}

解决方案

cellForRowAtIndex: method is called for "every" cell, so you're not supposed to do your database work in there, it's just responsible for creating "one" cell at a time.

So, move your observeEventType: call in viewDidLoad: or viewDidAppear: like:

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.ref = [[FIRDatabase database] reference];
    posts = [ref child:@"posts"];

    [posts observeEventType:FIRDataEventTypeValue withBlock:^(FIRDataSnapshot *snapshot)
     {
         self.allSnapshots = [NSMutableArray array];

         for (snapshot in snapshot.children)
         {
                 [self.allSnapshots addObject:snapshot];
         }

         [self.tableView reloadData]; // Refresh table view after getting data
     } // .. error ...
}

And in numberOfRowsForInSection:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section      
{
    return [self.allSnapshots count];
}

And in cellForRowAtIndex:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    RankingsCell *cell = [tableView dequeueReusableCellWithIdentifier:@"RankingsCell"];

    FIRDataSnapshot *snapshot = [self.allSnapshots objectAtIndex:indexPath.row]; 

    NSString *username = snapshot.value[@"Name"];
    NSString *date = snapshot.value[@"Date"];
    NSString *combatPower = snapshot.value[@"Combat Power"];
    NSString *pokemon = snapshot.value[@"Pokemon"];
    NSString *pokemonURL = snapshot.value[@"Pokemon Image"];
    NSString *picURL = snapshot.value[@"Profile Picture"];
    int CP = [combatPower intValue];

    cell.usernameOutlet.text = username;
    cell.dateOutlet.text = date;
    cell.combatPowerLabel.text = [NSString stringWithFormat:@"COMBAT POWER: %d", CP];
    cell.pokemonLabel.text = pokemon;
    [cell downloadUserImage:picURL];
    [cell downloadPokemonImage:pokemonURL];

    return cell;
}

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