大佬教程收集整理的这篇文章主要介绍了ios – uitablviewcell动态高度从systemLayoutSizeFittingSize不正确,大佬教程大佬觉得挺不错的,现在分享给大家,也给大家做个参考。
1 dequeueReusableCellWithIdentifier获取一个单元格
2然后调用[cell.contentView systemLayoutSizeFitTingSize:UILayoutFitTingCompressedSize]获取正确的高度.
但是在调试中,我发现当heightForRowATindexPath被调用时,我的单元格的宽度不是tableview的宽度,单元格的宽度与xib文件的宽度相同(因为在xcode6中,可以将xib大小设置为任何).所以从systemLayoutSizeFitTingSize得到的高度是不正确的.如何解决这个问题,以获得正确的单元格高度
从systemLayoutSizeFitTingSize获得的大小是不正确的,这个大小可能有宽度340(而设备是宽度为320的iPhone5),而340是根据单元格的xib文件的宽度
最后,我得到了解决方案,谢谢Ashish Gabani的帮助,其实解决方案包括2步:
1将单元框重置为tableView大小
2在调用systemLayoutSizeFitTingSize之前调用单元格的layoutSubView,在自定义单元格中,需要重写layoutSubViews方法.
这是解决这个问题的代码,我用红色方块来标记它们,享受它
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowATindexPath:(NSIndexPath *)indexPath { // Determine which reuse identifier should be used for the cell at this index path,// depending on the particular layout required (you may have just one,or may have many). NSString *reusEIDentifier = ...; // Dequeue a cell for the reuse identifier. // Note that this method will init and return a new cell if there isn't one available in the reuse pool,// so either way after this line of code you will have a cell with the correct consTraints ready to go. UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:reusEIDentifier]; // Configure the cell with content for the given indexPath,for example: // cell.textLabel.text = someTextForThisCell; // ... // Make sure the consTraints have been set up for this cell,since it may have just been created from scratch. // Use the following lines,assuming you are setTing up consTraints from within the cell's updateConsTraints method: [cell setNeedsupdateConsTraints]; [cell updateConsTraintsIfNeeded]; // If you are using multi-line UILabels,don't forget that the preferredMaxLayoutWidth needs to be set correctly. // Do it at this point if you are NOT doing it within the UITableViewCell subclass -[layoutSubviews] method. // For example: // cell.multiLineLabel.preferredMaxLayoutWidth = CGRectGetWidth(tableView.bounds); return cell; } - (CGFloat)tableView:(UITableView *)tableView heightForRowATindexPath:(NSIndexPath *)indexPath { // Determine which reuse identifier should be used for the cell at this index path. NSString *reusEIDentifier = ...; // Use a Dictionary of offscreen cells to get a cell for the reuse identifier,creaTing a cell and storing // it in the Dictionary if one hasn't already been added for the reuse identifier. // WARNING: Don't call the table view's dequeueReusableCellWithIdentifier: method here because this will result // in a memory leak as the cell is created but never returned from the tableView:cellForRowATindexPath: method! UITableViewCell *cell = [self.offscreenCells objectForKey:reusEIDentifier]; if (!cell) { cell = [[YourTableViewCellClass alloc] init]; [self.offscreenCells setObject:cell forKey:reusEIDentifier]; } // Configure the cell with content for the given indexPath,assuming you are setTing up consTraints from within the cell's updateConsTraints method: [cell setNeedsupdateConsTraints]; [cell updateConsTraintsIfNeeded]; // Set the width of the cell to match the width of the table view. This is important so that we'll get the // correct cell height for different table view widths if the cell's height depends on its width (due to // multi-line UILabels word wrapping,etC). We don't need to do this above in -[tableView:cellForRowATindexPath] // because it happens automatically when the cell is used in the table view. // Also note,the final width of the cell may not be the width of the table view in some cases,for example when a // section index is displayed along the right side of the table view. You must account for the reduced cell width. cell.bounds = CGRectMake(0.0f,0.0f,CGRectGetWidth(tableView.bounds),CGRectGetHeight(cell.bounds)); // Do the layout pass on the cell,which will calculate the frames for all the views based on the consTraints. // (Note that you must set the preferredMaxLayoutWidth on multi-line UILabels inside the -[layoutSubviews] method // of the UITableViewCell subclass,or do it manually at this point before the below 2 lines!) [cell setNeedsLayout]; [cell layoutIfNeeded]; // Get the actual height required for the cell's contentView CGFloat height = [cell.contentView systemLayoutSizeFitTingSize:UILayoutFitTingCompressedSize].height; // Add an extra point to the height to account for the cell separator,which is added between the bottom // of the cell's contentView and the bottom of the table view cell. height += 1.0f; return height; } // NOTE: Set the table view's estimatedRowHeight property instead of implemenTing the below method,UNLESS // you have extreme variability in your row heights and you notice the scroll inDicator "jumping" as you scroll. - (CGFloat)tableView:(UITableView *)tableView estimatedHeightForRowATindexPath:(NSIndexPath *)indexPath { // Do the minimal calculations required to be able to return an estimated row height that's // within an order of magnitude of the actual height. // For example: if ([self isTallCellATindexPath:indexPath]) { return 350.0f; } else { return 40.0f; } }
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