加载图像到自定义表视图细胞异步

问题描述：

目前，我正在开发一个应用程序中，我有获取Facebook相册的照片作为图库查看异步使用表格视图上使用下面的代码表视图单元格的按钮&放图片&显示：加载图像到自定义表视图细胞异步

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView 
{ 
    return 1; 
} 

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{ 
    NSLog(@"particulars..:%d",[particular count]); 
    int count=self.particular.count%3; 

    if(count==0) 
    { 
     return self.particular.count/3; 
    } 
    else 
    { 
     return (self.particular.count/3) +1; 
    } 
} 

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    static NSString *CellIdentifier = @"Cell1"; 
    CustomTableViewCell *cell = (CustomTableViewCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier]; 
    if (cell == nil) 
     { 
      [[NSBundle mainBundle] loadNibNamed:@"CustomTableViewCell" owner:self options:nil]; 
      cell = customcell; 
     } 


    UIActivityIndicatorView *spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray]; 

     dispatch_async(dispatch_get_global_queue(0,0), ^{ 
      NSString *buttonurl=[self.particular objectAtIndex:((indexPath.row)*3)+0]; 
      NSData * data = [[NSData alloc] initWithContentsOfURL: [NSURL URLWithString: buttonurl]]; 
      if (data == nil) 
       return; 
      dispatch_async(dispatch_get_main_queue(), ^{ 


       UIImage *image = [UIImage imageWithData:data]; 
       cell.accessoryType = UITableViewCellAccessoryNone; 
       cell.selectionStyle = UITableViewCellSelectionStyleNone; 
       cell.backgroundColor=[UIColor clearColor]; 
       [cell.first setBackgroundImage:image forState:UIControlStateNormal] ; 
       [cell.first addTarget:self action:@selector(original:) forControlEvents:UIControlEventTouchUpInside]; 
       [cell.first setContentMode:UIViewContentModeCenter] ; 
       cell.first.layer.cornerRadius = 10.0; 
       cell.first.layer.borderColor = [[UIColor grayColor]CGColor]; 
       cell.first.layer.borderWidth = 1.0f; 
       cell.first.backgroundColor=[UIColor clearColor]; 
       cell.first.tag = ((indexPath.row)*3)+1 ; 
       [spinner stopAnimating]; 
      }); 
      [data release]; 
     }); 

     if(((indexPath.row)*3)+3<[particular count]) 
     { 
      UIActivityIndicatorView *spinner2 = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray]; 
      UIActivityIndicatorView *spinner3 = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray]; 
      //spinner2.backgroundColor=[UIColor blackColor]; 
      CGRect frame= cell.second.frame; 
      spinner2.frame=frame; 
      //spinner2.frame=CGRectMake(112, y, 106, 106); 
      spinner2.hidesWhenStopped = YES; 
      [cell.second addSubview:spinner2]; 
      [spinner2 startAnimating]; 

      CGRect frame2= cell.third.frame; 
      spinner3.frame=frame2; 
      spinner3.hidesWhenStopped = YES; 
      [cell.third addSubview:spinner3]; 
      [spinner3 startAnimating]; 

      dispatch_async(dispatch_get_global_queue(0,0),^
      { 
       NSString *buttonurl=[self.particular objectAtIndex:((indexPath.row)*3)+1]; 
       NSData * data = [[NSData alloc] initWithContentsOfURL: [NSURL URLWithString: buttonurl]]; 

       NSString *buttonurl1=[self.particular objectAtIndex:((indexPath.row)*3)+2]; 
       NSData * data1 = [[NSData alloc] initWithContentsOfURL: [NSURL URLWithString: buttonurl1]]; 
       if (data == nil) 
        return; 
       dispatch_async(dispatch_get_main_queue(),^
       { 
        UIImage *image = [UIImage imageWithData:data]; 
        UIImage *image1 = [UIImage imageWithData:data1]; 

        [cell.second setBackgroundImage:image forState:UIControlStateNormal] ; 
        [cell.second addTarget:self action:@selector(original:) forControlEvents:UIControlEventTouchUpInside]; 
        [cell.second setContentMode:UIViewContentModeCenter] ; 
        cell.second.layer.cornerRadius = 10.0; 
        cell.second.layer.borderColor = [[UIColor grayColor]CGColor]; 
        cell.second.layer.borderWidth = 1.0f; 
        cell.second.backgroundColor=[UIColor clearColor]; 
        cell.second.tag = ((indexPath.row)*3)+2 ; 
        NSLog(@"cell.second.tag:%d",cell.second.tag); 

        [cell.third setBackgroundImage:image1 forState:UIControlStateNormal] ; 
        [cell.third addTarget:self action:@selector(original:) forControlEvents:UIControlEventTouchUpInside]; 
        [cell.third setContentMode:UIViewContentModeCenter] ; 
        cell.third.layer.cornerRadius = 10.0; 
        cell.third.layer.borderColor = [[UIColor grayColor]CGColor]; 
        cell.third.layer.borderWidth = 1.0f; 

        cell.third.backgroundColor=[UIColor clearColor]; 
        cell.third.tag = ((indexPath.row)*3)+3 ; 
        NSLog(@"cell.third.tag:%d",cell.third.tag); 
        [spinner2 stopAnimating]; 
        [spinner3 stopAnimating]; 

       }); 
       [data release]; 
      }); 


     } 
     else if(((indexPath.row)*3)+2<[particular count]) 
     { 
      UIActivityIndicatorView *spinner2 = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray]; 
      CGRect frame1 = CGRectMake(120, y, 106, 107); 
      spinner2.frame=frame1; 
      spinner2.hidesWhenStopped = YES; 
      [cell.second addSubview:spinner2]; 
      [spinner2 startAnimating]; 
      dispatch_async(dispatch_get_global_queue(0,0),^
      { 
       NSString *buttonurl=[self.particular objectAtIndex:((indexPath.row)*3)+1]; 
       NSData * data = [[NSData alloc] initWithContentsOfURL: [NSURL URLWithString: buttonurl]]; 
       if (data == nil) 
        return; 
       dispatch_async(dispatch_get_main_queue(),^
       { 
        UIImage *image = [UIImage imageWithData:data]; 
        [cell.second setBackgroundImage:image forState:UIControlStateNormal] ; 
        [cell.second addTarget:self action:@selector(original:) forControlEvents:UIControlEventTouchUpInside]; 
        [cell.second setContentMode:UIViewContentModeCenter] ; 
        cell.second.layer.cornerRadius = 10.0; 
        cell.second.layer.borderColor = [[UIColor grayColor]CGColor]; 
        cell.second.layer.borderWidth = 1.0f; 
        cell.second.backgroundColor=[UIColor clearColor]; 
        cell.second.tag = ((indexPath.row)*3)+2 ; 
        NSLog(@"cell.second.tag:%d",cell.second.tag); 
        [spinner2 stopAnimating]; 

       }); 
       [data release]; 
      });   
     } 
     else 
     { 
      cell.second.hidden = YES; 
      cell.third.hidden = YES; 
     } 
     y=y+106; 
     return cell; 
    }

此代码工作为我好，但问题是，当图像加载到按钮的表视图细胞含有那么如果我们向下滚动，然后它慢慢地显示图像，但在那之后，当我们向上滚动查看先前负载图像然后图像消失&它再次加载从开始&拿请告诉我在代码中犯的错误，或者我该如何解决这个问题？

的图片加载缓慢，它开始重新加载，因为可重复使用的tableview细胞。它的好，如果你在数组中添加这些影像和数组加载到的tableview – Dany 2013-02-26 12:02:45

答

我建议你使用这个AsyncImageView。我已经使用它，它创造奇迹。要调用此API：

ASyncImage *img_EventImag = alloc with frame; 
NSURL *url = yourPhotoPath; 
[img_EventImage loadImageFromURL:photoPath]; 
[self.view addSubView:img_EventImage]; // In your case you'll add in your TableViewCell.

与使用UIImageView相同。简单，它为你做大部分事情。 AsyncImageView在UIImageView中同时包含一个简单的类别，用于在iOS上异步加载和显示图像，以便它们不锁定UI，以及用于更高级功能的UIImageView子类。 AsyncImageView适用于URL，因此可以与本地或远程文件一起使用。

加载/下载的图像缓存在内存中，并在发生内存警告时自动清除。 AsyncImageView独立于UIImage缓存运行，但默认情况下，位于应用程序捆绑包根目录中的任何图像都将存储在UIImage缓存中，以避免重复缓存图像。

该库还可用于独立于UIImageView加载和缓存图像，因为它提供对底层加载和缓存类的直接访问。

答

有哪些做的工作的一些自定义库很好的为你

AsynchImageView
SDWebImage
AFNetworking图像扩展（如果你使用AF）

Lithu是正确的。你可以使用任何一个可以轻松完成工作的任务。 – 2013-02-26 13:19:36

答

据工作它应该做的方式。当您滚动表格视图时，就像消失的单元格已被释放，并且向后滚动单元格时出现。所以，你应该用一个解决方案来缓存图像，使他们不需要再次加载，如EGOImageView（here），AsyncImageView，SDWebImage等做

答

这是一个使用dispatch_async的解决方案。如果你正在从服务的URL不是用这种方法NSObject的地方服务被称为

-(void)loadProfilePicWithURL:(NSString *)strUrl tagV:(NSInteger)tagV{ 
isProfilePicLoaded = NO; 
//set media tag as indexPath.row 

//call this method from cellForRowAtIndexpPath 
//Pass the image URL --> strProfilePicURL 
//Load the image in bg and set to imgProfilePic 
//After loaded, send a notification with tag to table view to update the cell 


NSData *data=[NSData dataWithContentsOfURL:[NSURL URLWithString:strUrl]]; 
imgProfilePic=[UIImage imageWithData:data]; 

isProfilePicLoaded = YES; 
[[NSNotificationCenter defaultCenter] postNotificationName:@"reloadTableViewCell" object:[NSNumber numberWithInteger:tagV]]; 
}

呼叫从的cellForRowAtIndexPath

[self performSelectorInBackground:@selector(loadPic:) withObject:[NSNumber numberWithInteger:indexPath.row]];

这种方法实现

-(void)loadPic: (id)indexPath{ 
NSInteger conV=[indexPath integerValue]; 

NSObject *object=[Array objectAtIndex:conV]; 
[object loadProfilePicWithURL:object.url tagV:conV];

}

添加观察员通知NSObject

-(void)reloadTableViewCell:(NSNotification *)note{ 
NSInteger mediaTag = [[note object] integerValue]; 

[self reloadCellImage:mediaTag];

}

重新加载该表中的特定细胞。

-(void)reloadCellImage:(NSInteger)row{ 
NSObject *object = [self.receivedArray objectAtIndex:row]; 
NSIndexPath* rowToReload = [NSIndexPath indexPathForRow:row inSection:0]; 
customCell *cell = (customCell *)[self.tableView cellForRowAtIndexPath:rowToReload]; 
[cell.imgVw setImage:object.image];}

加载图像到自定义表视图细胞异步

相关推荐