Question

我正在开发一个应用程序，它将以视差类型UITableView显示来自服务器的数据，这是我的代码。一切都很好，但cell数据（图片等）不断从一个cell切换到另一个。{/ p>

- (void)viewDidLoad
{
    [self hasInternet];
    self.tableView.dataSource = self;
    self.tableView.delegate = self;
    [self loadData];
    self.edgesForExtendedLayout=UIRectEdgeNone;
    self.extendedLayoutIncludesOpaqueBars=NO;
    self.automaticallyAdjustsScrollViewInsets=NO;
    [super viewDidLoad];
}
- (void)viewWillAppear:(BOOL)animated
{
    [self scrollViewDidScroll:nil];
    [super viewWillAppear:animated];
    [self loadData];
    self.tableView.dataSource = self;
    self.tableView.delegate = self;
}
- (void) loadData{
    name = @"name";
    email = @"email";
    thumbnail = @"thumbnail";
    myObject = [[NSMutableArray alloc] init];
    NSData *jsonSource = [NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://URL.php"]];
    id jsonObjects = [NSJSONSerialization JSONObjectWithData:jsonSource options:NSJSONReadingMutableContainers error:nil];
    for (NSDictionary *dataDict in jsonObjects) {
        NSString *title_data = [dataDict objectForKey:@"fname"];
        NSString *title_data2 = [dataDict objectForKey:@"lname"];
        NSString *fulname = [NSString stringWithFormat:@"%@ %@", title_data, title_data2];
        NSString *emAil = [dataDict objectForKey:@"email"];
        NSString *thumbnail_data = [dataDict objectForKey:@"img"];
        thumbnail_data = [NSString stringWithFormat:@"http://URL/upload/%@",thumbnail_data];
        dictionary = [NSDictionary dictionaryWithObjectsAndKeys: fulname, name, emAil, email, thumbnail_data, thumbnail, nil];
        [myObject addObject:dictionary];
    }
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return myObject.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"parallaxCell";
    JBParallaxCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell=[[JBParallaxCell alloc]initWithStyle:
              UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
    }
    NSDictionary *tmpDict = [myObject objectAtIndex:indexPath.row];
    NSMutableString *text;
    text = [NSMutableString stringWithFormat:@"%@",[tmpDict objectForKeyedSubscript:name]];
    NSMutableString *mail;
    mail = [NSMutableString stringWithFormat:@"%@",[tmpDict objectForKeyedSubscript:email]];
    NSMutableString *images;
    images = [NSMutableString stringWithFormat:@"%@ ",[tmpDict objectForKey:thumbnail]];
    NSURL *url = [NSURL URLWithString:[tmpDict objectForKey:thumbnail]];
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSURL *url = [NSURL URLWithString:[tmpDict objectForKey:thumbnail]];
        NSData *data = [NSData dataWithContentsOfURL:url];
        dispatch_async(dispatch_get_main_queue(), ^{
            cell.parallaxImage.image = [[UIImage alloc]initWithData:data];
        });
    });
    cell.titleLabel.text = [NSString stringWithFormat:@"%@",text];
    cell.subtitleLabel.text = [NSString stringWithFormat:@"%@",mail];
    return cell;
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    NSArray *visibleCells = [self.tableView visibleCells];    
    for (JBParallaxCell *cell in visibleCells) {
        [cell cellOnTableView:self.tableView didScrollOnView:self.view];
    }
}

当我编译它时，它会显示我的所有数据，但随后会从一个单元格切换到另一个单元格。任何帮助将不胜感激。感谢

Answer 1

因为UITableView重用了单元格所以当你向下或向上滚动从表视图边界消失的前一个单元格时，重用。但是它的图像视图在上次使用时会有一个图像，因此您必须首先清除图像视图。所以把这一行

cell.parallaxImage.image = nil;

在调度队列之前

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

Answer 2

您可以使用此代码将图像保存在文档目录中，然后显示它。请更改变量名称。

NSString *imageURL = [[matcheListArr objectAtIndex:indexPath.row] valueForKey:@"thumbnail_image"];
NSURL *url = [NSURL URLWithString:imageURL];
NSArray *seperate = [[[matcheListArr objectAtIndex:indexPath.row] valueForKey:@"thumbnail_image"] componentsSeparatedByString:@"/"];
NSString *fileName = [NSString stringWithFormat:@"%@.png",[seperate objectAtIndex:seperate.count-1]];

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0]; // Get documents folder
NSString *dataPath = [documentsDirectory stringByAppendingPathComponent:@"/MyFolder"];
NSError *error;
if (![[NSFileManager defaultManager] fileExistsAtPath:dataPath])
    [[NSFileManager defaultManager] createDirectoryAtPath:dataPath withIntermediateDirectories:NO attributes:nil error:&error];
NSString *getImagePath = [dataPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@",fileName]];
UIImage *img = [UIImage imageWithContentsOfFile:getImagePath];
if ([img isKindOfClass:[UIImage class]]) {
    //Set Downloaded Image
    [cell.matchUserImageView setImage:img];
}
else {
    if ([[ValidationString sharedManager] isNullString:[[matcheListArr objectAtIndex:indexPath.row] valueForKey:@"thumbnail_image"]] == YES) {
        //Set Default Image
        [cell.matchUserImageView setImage:[UIImage imageNamed:@"photo_icon.png"]];
    }
    else{
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
            NSData *imageData = [NSData dataWithContentsOfURL:url];
            NSArray *seperate = [[[matcheListArr objectAtIndex:indexPath.row] valueForKey:@"thumbnail_image"] componentsSeparatedByString:@"/"];
            NSString *fileName = [NSString stringWithFormat:@"%@.png",[seperate objectAtIndex:seperate.count-1]];

            dispatch_async(dispatch_get_main_queue(), ^{
                // Update the UI
                [cell.matchUserImageView setImage:[UIImage imageWithData:imageData]];
                NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
                NSString *documentsDirectory = [paths objectAtIndex:0];
                NSString *dataPath = [documentsDirectory stringByAppendingPathComponent:@"/MyFolder"];
                NSString *savedImagePath = [dataPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@",fileName]];
                [imageData writeToFile:savedImagePath atomically:NO];
            });
        });
    }
}

在从服务器加载时，UITableView第一个条目和最后一个条目切换记录数据

2 个答案: