UITableViewCell with UITextView height in iOS 7?
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UITableViewCell with `UITextView` in iOS 7 posed unique challenges, especially when it came to dynamically resizing cells based on the content of their subviews. `UITextView`, a scrollable, multiline text view, required precise handling to ensure that cells' heights were appropriate. Below, we delve into techniques, challenges, and examples regarding the implementation of a `UITableViewCell` containing a `UITextView` that adjusts its height accordingly.
Dynamic Cell Height
Challenge
When using `UITextView` within a `UITableViewCell`, dynamically adjusting cell height based on content was non-trivial in iOS 7. Unlike its successors, iOS 7 did not provide intrinsic content size support for dynamic cell heights, necessitating manual calculations.
Solution Overview
To effectively manage dynamic heights, developers needed to:
- Measure the size of the `UITextView` content.
- Update the height of each `UITableView` cell by adjusting the `UITableView` `rowHeight` property or implementing delegate methods accurately.
- Employ either automatic dimension calculations or manual height adjustment strategies.
Example Implementation
The primary method to handle dynamic cell heights involved calculating the cell's content size manually. Here's a basic example:
• (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
• Text Size Calculation: `boundingRectWithSize:options:attributes:context:` is crucial for determining dynamic text size. • Font Consistency: Ensure the font attributes used in calculations match those used in the `UITextView`. • Padding Management: Properly manage padding to avoid clipping. Adjust padding based on your design needs.
• Incorrect Constraints: Without proper constraints, cell height calculations can return incorrect sizes. • Performance Issues: Dynamically calculating heights in `heightForRowAtIndexPath:` can lead to performance bottlenecks in large datasets. Cache and reuse calculated sizes where possible. • Content Changes: When `UITextView` content changes frequently, ensure that you reload cells' heights using `beginUpdates` and `endUpdates` on the `UITableView`. • Scrolling: By default, `UITextView` is scrollable. For non-scrollable configurations, ensure scrolling is disabled to let the `UITextView` expand naturally. • User Interaction: Consider how interactive elements within the `UITextView`, such as links or custom gestures, will behave in dynamically-sized cells. • Cache calculated height values where feasible to minimize recalculations. • Use estimated row heights judiciously to optimize initial layout time and smooth scrolling.
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Step through 300+ coding interview problems with animated visualisers that show the data structure changing as the code runs. The Blind 75 are free.