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https://github.com/konstantinpavlikhin/kspautomaticheightcalculationtablecellview
A useful superclass for a custom view-based NSTableView's cell.
https://github.com/konstantinpavlikhin/kspautomaticheightcalculationtablecellview
cell constraints macos nstablecellview nstableview
Last synced: 3 months ago
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A useful superclass for a custom view-based NSTableView's cell.
- Host: GitHub
- URL: https://github.com/konstantinpavlikhin/kspautomaticheightcalculationtablecellview
- Owner: konstantinpavlikhin
- License: mit
- Created: 2014-11-09T11:36:56.000Z (about 10 years ago)
- Default Branch: master
- Last Pushed: 2016-09-05T11:33:13.000Z (over 8 years ago)
- Last Synced: 2024-10-03T12:33:27.058Z (4 months ago)
- Topics: cell, constraints, macos, nstablecellview, nstableview
- Language: Objective-C
- Homepage:
- Size: 755 KB
- Stars: 39
- Watchers: 8
- Forks: 8
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Contributing: CONTRIBUTING.md
- License: LICENSE.md
Awesome Lists containing this project
README
## KSPAutomaticHeightCalculationTableCellView
[](https://cocoapods.org/pods/KSPAutomaticHeightCalculationTableCellView)
[](https://cocoapods.org/pods/KSPAutomaticHeightCalculationTableCellView)
[](https://cocoapods.org/pods/KSPAutomaticHeightCalculationTableCellView)
A useful superclass for a custom view-based `NSTableView`’s cell.
## Sample Application
There is a simple application that demonstrates `KSPAutomaticHeightCalculationTableCellView` in action. The app shows a single window with an embedded split view. The left pane has a fixed-height cells (`AHCUserTableCellView`) that represent some fictional users. The right pane has cells (`AHCMessageTableCellView`) whose heights depend both on their textual content and a column width. When window is resized the table view on the right is notified to re-query the row heights from the delegate.
## How To Use
#### Your custom cell class should inherit from `KSPAutomaticHeightCalculationTableCellView`
This is how it used to look in Objective-C:
```objective-c
#import
@interface MyLovelyCell : KSPAutomaticHeightCalculationTableCellView
…
@end
```
#### Put your cell into a separate XIB and let the `KSPAutomaticHeightCalculationTableCellView` know how to find it at runtime
It is generally a good idea to put your cell into a separate XIB, but usage of a `KSPAutomaticHeightCalculationTableCellView` makes this mandatory.
By default `KSPAutomaticHeightCalculationTableCellView` will look for a nib file named exactly like your cell's subclass in a main bundle.
That is, if you call your cell class `MyLovelyCell` you have to name your XIB `MyLovelyCell.xib`. This xib should contain one and only one root view of MyLovelyCell class. You still can have an arbitrary number of other objects in a XIB, though.
You can customize the behaviour by overriding the following class methods:
```objective-c
+ (nonnull NSString*) correspondingNibName
{
return @"SomethingDifferent";
}
```
```objective-c
+ (nonnull NSBundle*) correspondingBundle
{
return [NSBundle bundle...];
}
```
#### Decide whether your custom table cell should have a variable height
**Cell has a variable height** == **Cell's height depends on a represented object value** `OR` **cell's height depends on cell's width**.
By default, `KSPAutomaticHeightCalculationTableCellView` assumes that your cell has a variable height, since this is the basic reason to use the class in your project at all.
Override `+hasFixedHeight` and return `YES` if your cell's height is really fixed.
```objective-c
+ (BOOL) hasFixedHeight
{
return YES;
}
```
In this case `KSPAutomaticHeightCalculationTableCellView` will cache the height after it will be calculated for the first time. Subsequent calls to `+heightWithRepresentedObject:width:` will return the stored value.
#### Layout your cell via Auto Layout
This step is also mandatory. `KSPAutomaticHeightCalculationTableCellView` only functions in Auto Layout-enabled mode. There is no point of using the class if you perform manual frame computations.
**Attention, this part is really important**:
After you add layout constraints, the height of your cell __should be unambiguous__! This means, height have to be constraint either directly (via explicit height constraint, which will render `KSPAutomaticHeightCalculationTableCellView` usage pretty pointless, since you already know the height value) or in a derived-fashion (in which height of a cell somehow depends on a geometry of its subviews, and the geometry, in its turn, depends on content).
Remember it, cause if you leave your cell view's height ambigous you will end up with a table view rows having a zero height.
#### Implement a `NSTableViewDelegate` method `-tableView:heightOfRow:`
```objective-c
- (CGFloat) tableView: (NSTableView*) tableView heightOfRow: (NSInteger) row
{
// Get the width of a column in which the cell should reside.
CGFloat columnWidth = [tableView tableColumnWithIdentifier: @“MainColumn”].width;
// Let the KSPAutomaticHeightCalculationTableCellView to calculate the preffered cell height for you.
return [MyLovelyCell heightWithRepresentedObject: # width: columnWidth];
}
```
At this point `KSPAutomaticHeightCalculationTableCellView` will create a prototype cell instance, set its `objectValue` property to the passed value, constrain its width to the `columnWidth` and calculate the minimum required height.
#### Make sure you don't make unnecessary work in your table cell view prototype
When `KSPAutomaticHeightCalculationTableCellView` instantiates a cell for measurement purposes it sets its boolean `prototype` property to `YES`. If you happen to do some heavy-lifting in your table cell view subclass, for example, doing expensive calculations in response to an `objectValue` change, please refrain from doing so if the calculation result doesn't affect the layout.
```objective-c
if(!self.prototype)
{
// Do some fancy visual effects pre-calculation (image caching, data detection and so on...).
}
else
{
// This cell is a prototype that is being reused for a row height calculation (possibly hundreds times per second).
}
```
That's it!