iOS - 在單元格中更改背景視圖時的延遲tableview

我只想先說我一直在尋找這個問題，但還沒找到類似於我的問題的東西。我想要做的是用圖像改變每個單元格的背景。我有三個圖像，「上，中，下」圖像。當我放置這些背景時，tableview在滾動上會變得遲緩。這就是我的做法：iOS - 在單元格中更改背景視圖時的延遲tableview

topImage = [[UIImage imageNamed:@"table_bg_top.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(10, 10, 0, 10)]; 
middleImage = [[UIImage imageNamed:@"table_bg_middle.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(10, 10, 0, 10)]; 
bottomImage = [[UIImage imageNamed:@"table_bg_bottom.png"] resizableImageWithCapInsets:UIEdgeInsetsMake(10, 10, 10, 10)];

這三個圖像在視圖加載時僅初始化一次。然後我有以下幾點：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    UITableViewCell *cell; 
     switch (indexPath.row) { 
      case 1: 
       cell = [tableView dequeueReusableCellWithIdentifier:@"TopCell"]; 
       [(UIImageView *)[cell viewWithTag:1] setImage:topImage]; 
       ((UILabel *)[cell viewWithTag:2]).text = @"First name"; 
       ((UILabel *)[cell viewWithTag:3]).text = firstName; 
       break; 
      case 2: 
       cell = [tableView dequeueReusableCellWithIdentifier:@"MiddleCell"]; 
       [(UIImageView *)[cell viewWithTag:1] setImage:middleImage]; 
       ((UILabel *)[cell viewWithTag:2]).text = @"Last name"; 
       ((UILabel *)[cell viewWithTag:3]).text = lastName; 
       break; 
      case 3: 
       cell = [tableView dequeueReusableCellWithIdentifier:@"MiddleCell"]; 
       [(UIImageView *)[cell viewWithTag:1] setImage:middleImage]; 
       ((UILabel *)[cell viewWithTag:2]).text = @"Birth"; 
       ((UILabel *)[cell viewWithTag:3]).text = [formatter stringFromDate:birth]; 
       break; 
      case 4: 
       cell = [tableView dequeueReusableCellWithIdentifier:@"MiddleCell"]; 
       [(UIImageView *)[cell viewWithTag:1] setImage:middleImage]; 
       ((UILabel *)[cell viewWithTag:2]).text = @"Gender"; 
       ((UILabel *)[cell viewWithTag:3]).text = gender; 
       break; 
      case 5: 
       cell = [tableView dequeueReusableCellWithIdentifier:@"MiddleCell"]; 
       [(UIImageView *)[cell viewWithTag:1] setImage:middleImage]; 
       ((UILabel *)[cell viewWithTag:2]).text = @"Unit"; 
       ((UILabel *)[cell viewWithTag:3]).text = unit; 
       break; 
      case 6: 
       cell = [tableView dequeueReusableCellWithIdentifier:@"MiddleCell"]; 
       [(UIImageView *)[cell viewWithTag:1] setImage:middleImage]; 
       ((UILabel *)[cell viewWithTag:2]).text = @"Height"; 
       if([unit isEqualToString:@"mt"]) 
        ((UILabel *)[cell viewWithTag:3]).text = [NSString stringWithFormat:@"%d cm", (int)(height.floatValue*100)]; 
       else 
        ((UILabel *)[cell viewWithTag:3]).text = [NSString stringWithFormat:@"%d foot %d inches", (int) round((height.floatValue*100*CM_TO_INCH))/12, (int)round((height.floatValue*100*CM_TO_INCH)) % 12]; 
       break; 
      case 7: 
       cell = [tableView dequeueReusableCellWithIdentifier:@"BottomCell"]; 
       [(UIImageView *)[cell viewWithTag:1] setImage:bottomImage]; 
       ((UILabel *)[cell viewWithTag:2]).text = @"Weight"; 
       if([unit isEqualToString:@"mt"]) 
        ((UILabel *)[cell viewWithTag:3]).text = [NSString stringWithFormat:@"%d kg", weight.integerValue]; 
       else 
        ((UILabel *)[cell viewWithTag:3]).text = [NSString stringWithFormat:@"%d pounds",(int) round((weight.floatValue*KG_TO_LBS))]; 
       break; 
      default: 
       break; 
     } 

    return cell; 
}

我有一個自定義單元格，具有三個不同的標識符（頂部，中間和底部）。這是造成延遲：[(UIImageView *)[cell viewWithTag:1] setImage:image];。 UIImageView與單元格一樣大，以獲得背景效果。

謝謝！

來源

2012-10-31 Carnal

我發現了這個問題。它與：resizableImageWithCapInsets:UIEdgeInsetsMake(10, 10, 0, 10)，它滯後，因爲它多次繪製相同的圖像來拉伸它。所以我將不得不讓這個圖像像單元一樣大，以擺脫滯後。

如果有人找到替代解決方案，請填寫我的名單，如果它有效，我會接受它！

來源

2012-10-31 11:18:37 Carnal

iOS - 在單元格中更改背景視圖時的延遲tableview

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