UITableView數據顯示多次滾動

Question

我有一個UITableView數據顯示，但當它滾動數據（UILabel）要麼消失，要麼他們一遍又一遍地重複添加在彼此的頂部。每當我滾動每一次細胞交換數據。

這裏是我的cellForRowAtIndexPath:代碼

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
    { 
     static NSString *cellIdentifier = @"Cell"; 

     UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier]; 

     if(cell == nil) { 
      cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier]; 

     } 

     cell.selectionStyle = UITableViewCellSelectionStyleNone; 

     // configure the cell's background 
     UIImageView *gradient = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"gradient"]]; 
     [cell.contentView addSubview:gradient]; 

     // configure the cell's label 
     UILabel *nameLabel = [[UILabel alloc] initWithFrame:CGRectMake(50, 130, 300, 44)]; 

     // grab a reference to the label's text from the tableData 
     nameLabel.text = [name objectAtIndex:indexPath.row]; 
     nameLabel.textColor = [UIColor blackColor]; 
     nameLabel.font = [UIFont fontWithName:@"DIN-Bold" size:12]; 
     nameLabel.backgroundColor = [UIColor clearColor]; 

     // set the autoReiszing mask -- this way if the label spills over the editing 
     // [icon?] then the text will trail off in ... 
     nameLabel.autoresizingMask = UIViewAutoresizingFlexibleWidth; 

     [cell.contentView addSubview:nameLabel]; 

     // configure the cell's label 
     UILabel *tableTextViewLbl = [[UILabel alloc] initWithFrame:CGRectMake(50, 80, 220, 50)]; 

     // grab a reference to the label's text from the tableData 
     tableTextViewLbl.text = [message objectAtIndex:indexPath.row]; 
     tableTextViewLbl.textColor = [UIColor blackColor]; 
     tableTextViewLbl.font = [UIFont fontWithName:@"DIN" size:10]; 
     tableTextViewLbl.backgroundColor = [UIColor clearColor]; 
     tableTextViewLbl.autoresizingMask = UIViewAutoresizingFlexibleWidth; 

     [cell.contentView addSubview:tableTextViewLbl]; 

     // configure the cell's label 
     UILabel *tableTimeStampViewLbl = [[UILabel alloc] initWithFrame:CGRectMake(50, 30, 200, 50)]; 

     // grab a reference to the label's text from the tableData 
     tableTimeStampViewLbl.text = [timeStamp objectAtIndex:indexPath.row]; 
     tableTimeStampViewLbl.textColor = [UIColor lightGrayColor]; 
     tableTimeStampViewLbl.font = [UIFont fontWithName:@"DIN" size:7]; 
     tableTimeStampViewLbl.backgroundColor = [UIColor clearColor]; 
     tableTimeStampViewLbl.autoresizingMask = UIViewAutoresizingFlexibleWidth; 

     [cell.contentView addSubview:tableTimeStampViewLbl]; 

    // UIImageView *image; 
    // UIImage *image1=[UIImage imageNamed:@"rest.png"]; 
    // image=[[UIImageView alloc]initWithImage:image1]; 
    // image.frame=CGRectMake(10,30,40,30); 
    // 
    // [cell.contentView addSubview:image]; 
    // 


     return cell; 

    } 

Answer 1

您要爲每一個細胞被加載/重新加載到視圖時間創建一個UILabel實例。這不是如何完成的。相反，將UILabel作爲屬性（可能是IBOutlet）添加到UITableView子類中，並在cellForRowAtIndexPath:中進行更改。

所以你會有一個新的類，繼承自UITableViewCell - 我們稱之爲MyCustomCell。

在MyCustomCell.h：

@interface MyCustomCell : UITableViewCell 

@property (weak, nonatomic) IBOutlet UILabel *nameLabel; 

@end 

MyCustomCell.xib將限定的UILabel位置和構型，當然需要將與nameLabel屬性相關聯。

在cellForRowAtIndexPath中，而不是實例化一個新的UILabel，您只需引用cell.nameLabel並更改文本。一定要定義爲resuseIdentifier在Interface Builder細胞類和使用實例是：

MyCustomCell *cell = [tableView dequeueReusableCellWithIdentifier:@"MyIdentifier"]; 

if (!cell) { 
    cell = [[MyCustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"MyIdentifier"]; 

} 

Answer 2

用這種方式

if (cell == nil) { 
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier]; 
} 
else{ 
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier]; 
} 

但是考慮自定義單元格是最好的答案。檢查此鏈接提供最佳解決方案custom cell

Answer 3

在您按照我的回答之前，我想告訴您，以下代碼對內存管理不利，因爲它將爲每行UITableView創建新單元，因此請小心。

但是最好使用，當UITableView有限行（大約50-100可能是）那麼下面的代碼對你有幫助，如果它適合你使用它。

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

    NSString *CellIdentifier = [NSString stringWithFormat:@"S%1dR%1d",indexPath.section,indexPath.row]; 
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; 
    if(cell == nil) 
    { 
     cell = [[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; 

     /// Put your code here 
    } 

    return cell; 
} 

如果您的行數有限，那麼這是最適合您的代碼。

Answer 4

首先您需要了解「UITableView如何工作？」其實UITableView的電池概念是，每次您滾動表視圖，它不是爲您創造新的細胞，它只是重用細胞與cellIdentifier

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];的幫助，那時候我們只是需要更新單元格的數據..多數民衆贊成它..最好。快樂編碼...謝謝...嗯，我這樣做只是......你可以看到下面:::

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
    { 
     static NSString *cellIdentifier = @"Cell"; 

    UILabel *nameLabel = nil; 

    UILabel *tableTextViewLbl= nil; 

    UILabel *tableTimeStampViewLbl= nil; 
    //Here we are , reuse the cells... 
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier]; 



    if(cell == nil) { 
     cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier]; 

     cell.selectionStyle = UITableViewCellSelectionStyleNone; 

     // configure the cell's background 
     UIImageView *gradient = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"gradient"]]; 
     [cell.contentView addSubview:gradient]; 

     // configure the cell's label 
     nameLabel = [[UILabel alloc] initWithFrame:CGRectMake(50, 130, 300, 44)]; 

     // grab a reference to the label's text from the tableData 
     nameLabel.textColor = [UIColor blackColor]; 
     nameLabel.font = [UIFont fontWithName:@"DIN-Bold" size:12]; 
     nameLabel.backgroundColor = [UIColor clearColor]; 
     nameLabel.tag = 111;//Giving this component to tag so we can access it 

     // set the autoReiszing mask -- this way if the label spills over the editing 
     // [icon?] then the text will trail off in ... 
     nameLabel.autoresizingMask = UIViewAutoresizingFlexibleWidth; 

     [cell.contentView addSubview:nameLabel]; 

     // configure the cell's label 
     tableTextViewLbl = [[UILabel alloc] initWithFrame:CGRectMake(50, 80, 220, 50)]; 
     tableTextViewLbl.textColor = [UIColor blackColor]; 
     tableTextViewLbl.font = [UIFont fontWithName:@"DIN" size:10]; 
     tableTextViewLbl.backgroundColor = [UIColor clearColor]; 
     tableTextViewLbl.autoresizingMask = UIViewAutoresizingFlexibleWidth; 
     tableTextViewLbl.tag = 222;//Giving this component to tag so we can access it 
     [cell.contentView addSubview:tableTextViewLbl]; 

     // configure the cell's label 
     tableTimeStampViewLbl = [[UILabel alloc] initWithFrame:CGRectMake(50, 30, 200, 50)]; 
     tableTimeStampViewLbl.textColor = [UIColor lightGrayColor]; 
     tableTimeStampViewLbl.font = [UIFont fontWithName:@"DIN" size:7]; 
     tableTimeStampViewLbl.backgroundColor = [UIColor clearColor]; 
     tableTimeStampViewLbl.autoresizingMask = UIViewAutoresizingFlexibleWidth; 
     tableTimeStampViewLbl.tag = 333;//Giving this component to tag so we can access it 
     [cell.contentView addSubview:tableTimeStampViewLbl]; 
    } 



    nameLabel = (UILabel*)[cell.contentView viewWithTag:111];//Here we access the name label with the help of tag, is that we have assigned tag while making the componant. 
    nameLabel.text = [name objectAtIndex:indexPath.row]; 


    tableTextViewLbl = (UILabel*)[cell.contentView viewWithTag:222];//Here we access the name label with the help of tag, is that we have assigned tag while making the componant. 
    // grab a reference to the label's text from the tableData 
    tableTextViewLbl.text = [message objectAtIndex:indexPath.row]; 


    tableTimeStampViewLbl = (UILabel*)[cell.contentView viewWithTag:333];//Here we access the name label with the help of tag, is that we have assigned tag while making the componant. 
    // grab a reference to the label's text from the tableData 
    tableTimeStampViewLbl.text = [timeStamp objectAtIndex:indexPath.row]; 


    return cell; 

} 

Answer 5

只需添加以下代碼

NSArray *subviews = [[NSArray alloc] initWithArray:cell.contentView.subviews]; 
for (UILabel *subview in subviews) 
{ 
    [subview removeFromSuperview]; 
} 
[subviews release]; 
subviews = nil; 

後 -

if (cell == nil) 
{ 
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault  reuseIdentifier:CellIdentifier]; 
} 

然後添加你的代碼。