#uitableviewcell

When you ask the contentView of UITableViewCell for its size the returned frame is only correct if the cell has already been rendered or the cell does not have any type of accessory view or accessory type. This is a problem if you want to calculate the height of a table view cell based on its layout as you have no chance to figure out the size of the contentView inside the tableView:heightForRowAtIndexPath: delegate method.

Today... after a long vacation :) I will explain how to - dynamically - update the height of statics UITableViewCell. In Swift. I suppose that you are in a viewcontroller that inherits from the UITableViewController and that you are ready to use the tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) function.

Write your code there like below:

override func tableView(tableView: UITableView, heightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat { let dynamicRowIndexPath = NSIndexPath(forRow: 2, inSection: 0) if !indexPath.isEqual(dynamicRowIndexPath) { return super.tableView(tableView, heightForRowAtIndexPath: indexPath) } else { return iWannaBigCell == true ? 250 : 80 } }

and where the new height for the cell is required, just write these two lines:

self.tableView.beginUpdates() self.tableView.endUpdates()

* When the table view cell separator insets are non-zero (i.e. the default), the default background color of the table view cell (white on iOS7) shows through in the gap between the separator and the edge of the cell. * When a cell is selected, it's separator and the separator of the cell above it are hidden, resulting in the cell background showing completely in the cell above in the gap where the hidden separator would have been. * There is no gap on the selected cell, because unlike the backgroundView, the selectedBackgroundView extends to the full height of the cell and fills it completely.

AFNetworking có một category rất hữu ích cho việc download ảnh là UIImageView+AFNetworking. Ta thường hay dùng hàm này trong các method để configure cho một custom UITableViewCell chứa một UIImageView. Ví dụ:

- (void)configureForSearchResult:(SearchResult *)searchResult{ self.nameLabel.text = searchResult.name; self.artistNameLabel.text = searchResult.artistName; NSURL *thumbnailURL = [NSURL URLWithString:searchResult.artworkURL60]; UIImage *placeholderImage = [UIImage imageNamed:@"Placeholder"] [self.artworkImageView setImageWithURL:thumbnailURL placeholderImage:placeholderImage]; }

Nên nhớ rằng UITableViewCell có thể được tái sử dụng. Vì vậy, khi ta scroll table thì một vài cell sẽ được tái sử dụng trong khi đó image của cell đó vẫn đang được AFNetworking download. Ta không cần image đó nữa mà thay vào đó download image mới, vì vậy ta nên cancel việc download của các image cũ. Để làm vậy, ta tận dụng hàm prepareForReuse của UITableViewCell:

I have created a custom UITableViewCell loading it from a xib file following the helpful guidance of; How do you load custom UITableViewCells from xib files.

I only want this custom cell for the first row in my UITableView, the others are simple labels and the standard UITableViewCell is fine.

The problem is when I include the custom cell the whole UITableViewisn’t shown and the screen is blank…

自定义UITableViewCell自动布局的文章网上又挺多的，但是大部分都是采用的xib进行布局，所以这一块其实水挺深的。经过自己的实践和不断的查找资料，终于实现了使用纯VFL布局，实现方式在这里和大家一起分享一下，Demo比较简单

首先我们新建一个工程，命名为CustomCellWithVFLDemo，如下图所示：

让我们的ViewController继承UITableViewController。继承UITableViewController能帮我们省不少事情。

新建CustomCell，我们在其中新建一个UILabel，叫contentLabel，用于展示文本数据并允许换行。

为contentLabel设置约束，这里我们的约束可以看做Margin(5,5,5,5)。

在ViewController中添加一个原型cell，动态计算高度的时候使用。

The answer by xlsmearlx made mine work: