加載圖像到自定義表視圖細胞異步

目前，我正在開發一個應用程序中，我有獲取Facebook相冊的照片作爲圖庫查看異步使用表格視圖上使用下面的代碼表視圖單元格的按鈕&放圖片&顯示：加載圖像到自定義表視圖細胞異步

- (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; 
    }

此代碼工作爲我好，但問題是，當圖像加載到按鈕的表視圖細胞含有那麼如果我們向下滾動，然後它慢慢地顯示圖像，但在那之後，當我們向上滾動查看先前負載圖像然後圖像消失&它再次加載從開始&拿請告訴我在代碼中犯的錯誤，或者我該如何解決這個問題？

來源

2013-02-26 Vishal

的圖片加載緩慢，它開始重新加載，因爲可重複使用的tableview細胞。它的好，如果你在數組中添加這些影像和數組加載到的tableview – Dany 2013-02-26 12:02:45

我建議你使用這個AsyncImageView。我已經使用它，它創造奇蹟。要調用此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.

與使用UIImageView相同。簡單，它爲你做大部分事情。 AsyncImageView在UIImageView中同時包含一個簡單的類別，用於在iOS上異步加載和顯示圖像，以便它們不鎖定UI，以及用於更高級功能的UIImageView子類。 AsyncImageView適用於URL，因此可以與本地或遠程文件一起使用。

加載/下載的圖像緩存在內存中，並在發生內存警告時自動清除。 AsyncImageView獨立於UIImage緩存運行，但默認情況下，位於應用程序捆綁包根目錄中的任何圖像都將存儲在UIImage緩存中，以避免重複緩存圖像。

該庫還可用於獨立於UIImageView加載和緩存圖像，因爲它提供對底層加載和緩存類的直接訪問。

來源

2013-02-26 12:13:55 Rushi

有哪些做的工作的一些自定義庫很好的爲你

AsynchImageView
SDWebImage
AFNetworking圖像擴展（如果你使用AF）

來源

2013-02-26 12:04:20

Lithu是正確的。你可以使用任何一個可以輕鬆完成工作的任務。 – 2013-02-26 13:19:36

據工作它應該做的方式。當您滾動表格視圖時，就像消失的單元格已被釋放，並且向後滾動單元格時出現。所以，你應該用一個解決方案來緩存圖像，使他們不需要再次加載，如EGOImageView（here），AsyncImageView，SDWebImage等做

來源

2013-02-26 12:04:21 CainaSouza

這是一個使用dispatch_async的解決方案。如果你正在從服務的URL不是用這種方法NSObject的地方服務被稱爲

-(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]]; 
}

呼叫從的cellForRowAtIndexPath

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

這種方法實現

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

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

}

添加觀察員通知NSObject

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

[self reloadCellImage:mediaTag];

}

重新加載該表中的特定細胞。

-(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];}

來源

2015-03-03 11:52:51

加載圖像到自定義表視圖細胞異步

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