How to get UITableView from UITableViewCell?
IphoneIosObjective CXcodeTableviewIphone Problem Overview
I have a UITableViewCell
which is linked to an object and I need to tell if the cell is visible. From the research I've done, this means I need to somehow access the UITableView
that contains it (from there, there are several ways to check if it's visible). So I'm wondering if UITableViewCell
has a pointer to the UITableView
, or if there was any other way to get a pointer from the cell?
Iphone Solutions
Solution 1 - Iphone
To avoid checking the iOS version, iteratively walk up the superviews from the cell's view until a UITableView is found:
Objective-C
id view = [cellInstance superview];
while (view && [view isKindOfClass:[UITableView class]] == NO) {
view = [view superview];
}
UITableView *tableView = (UITableView *)view;
Swift
var view = cellInstance.superview
while (view != nil && (view as? UITableView) == nil) {
view = view?.superview
}
if let tableView = view as? UITableView {
tableView.beginUpdates()
tableView.endUpdates()
}
Solution 2 - Iphone
In iOS7 beta 5 UITableViewWrapperView
is the superview of a UITableViewCell
. Also UITableView
is superview of a UITableViewWrapperView
.
So for iOS 7 the solution is
UITableView *tableView = (UITableView *)cell.superview.superview;
So for iOSes up to iOS 6 the solution is
UITableView *tableView = (UITableView *)cell.superview;
Solution 3 - Iphone
##Swift 5 extension ###Recursively
extension UIView {
func parentView<T: UIView>(of type: T.Type) -> T? {
guard let view = superview else {
return nil
}
return (view as? T) ?? view.parentView(of: T.self)
}
}
extension UITableViewCell {
var tableView: UITableView? {
return parentView(of: UITableView.self)
}
}
###Using loop
extension UITableViewCell {
var tableView: UITableView? {
var view = superview
while let v = view, v.isKind(of: UITableView.self) == false {
view = v.superview
}
return view as? UITableView
}
}
Solution 4 - Iphone
Before iOS7, the cell's superview was the UITableView
that contained it. As of iOS7 GM (so presumably will be in the public release as well) the cell's superview is a UITableViewWrapperView
with its superview being the UITableView
. There are two solutions to the problem.
UITableViewCell
category
Solution #1: Create a @implementation UITableViewCell (RelatedTable)
- (UITableView *)relatedTable
{
if ([self.superview isKindOfClass:[UITableView class]])
return (UITableView *)self.superview;
else if ([self.superview.superview isKindOfClass:[UITableView class]])
return (UITableView *)self.superview.superview;
else
{
NSAssert(NO, @"UITableView shall always be found.");
return nil;
}
}
@end
This is a good drop-in replacement to using cell.superview
, makes it easy to refactor your existing code -- just search and replace with [cell relatedTable]
, and throw in an assert to ensure that if the view hierarchy changes or reverts in the future it will show up immediately in your tests.
UITableView
reference to UITableViewCell
Solution #2: Add a Weak @interface SOUITableViewCell
@property (weak, nonatomic) UITableView *tableView;
@end
This is a much better design, though it will require a bit more code refactoring to use in existing projects. In your tableView:cellForRowAtIndexPath
use SOUITableViewCell as your cell class or make sure your custom cell class is subclassed from SOUITableViewCell
and assign the tableView to the cell's tableView property. Inside the cell you can then refer to the containing tableview using self.tableView
.
Solution 5 - Iphone
If it is visible then it has a superview. And ... surprise ... the superview is an UITableView object.
However, having a superview is no guarantee for being on screen. But UITableView provides methods to determine which cells are visible.
And no, there is no dedicated reference from a cell to a table. But when you subclass UITableViewCell you may introduce one and set it upon creation. (I did that myself a lot before I thought of the subview hierarchy.)
Update for iOS7: Apple has changed the subview hierarchy here. As usual when working with things that are not detailled documented, there is always a risk that things change. It is far saver to "crawl up" the view hierarchy until a UITableView object is eventually found.
Solution 6 - Iphone
Whatever you may end up managing to do by calling super view or via the responder chain is going to be very fragile. The best way to do this, if the cells wants to know something, is to pass an object to the cell that responds to some method that answers the question the cell wants to ask, and have the controller implement the logic of determining what to answer (from your question I guess the cell wants to know if something is visible or not).
Create a delegate protocol in the cell, set the delegate of the cell the tableViewController and move all the ui "controlling" logic in the tableViewCotroller.
The table view cells should be dum view that will only display information.
Solution 7 - Iphone
Swift 2.2 solution.
An extension for UIView that recursively searches for a view with a specific type.
import UIKit
extension UIView {
func lookForSuperviewOfType<T: UIView>(type: T.Type) -> T? {
guard let view = self.superview as? T else {
return self.superview?.lookForSuperviewOfType(type)
}
return view
}
}
or more compact (thanks to kabiroberai):
import UIKit
extension UIView {
func lookForSuperviewOfType<T: UIView>(type: T.Type) -> T? {
return superview as? T ?? superview?.superviewOfType(type)
}
}
In your cell you just call it:
let tableView = self.lookForSuperviewOfType(UITableView)
// Here we go
Mind that UITableViewCell is added on the UITableView only after cellForRowAtIndexPath execution.
Solution 8 - Iphone
I created a category on UITableViewCell to get its parent tableView:
@implementation UITableViewCell (ParentTableView)
- (UITableView *)parentTableView {
UITableView *tableView = nil;
UIView *view = self;
while(view != nil) {
if([view isKindOfClass:[UITableView class]]) {
tableView = (UITableView *)view;
break;
}
view = [view superview];
}
return tableView;
}
@end
Best,
Solution 9 - Iphone
Here is the Swift version based on above answers. I have generalized into ExtendedCell
for later usage.
import Foundation
import UIKit
class ExtendedCell: UITableViewCell {
weak var _tableView: UITableView!
func rowIndex() -> Int {
if _tableView == nil {
_tableView = tableView()
}
return _tableView.indexPathForSelectedRow!.row
}
func tableView() -> UITableView! {
if _tableView != nil {
return _tableView
}
var view = self.superview
while view != nil && !(view?.isKindOfClass(UITableView))! {
view = view?.superview
}
self._tableView = view as! UITableView
return _tableView
}
}
Hope this help :)
Solution 10 - Iphone
I based this solution on Gabe's suggestion that UITableViewWrapperView
object is the superview of UITableViewCell
object in iOS7 beta5 .
Subclass UITableviewCell
:
- (UITableView *)superTableView
{
return (UITableView *)[self findTableView:self];
}
- (UIView *)findTableView:(UIView *)view
{
if (view.superview && [view.superview isKindOfClass:[UITableView class]]) {
return view.superview;
}
return [self findTableView:view.superview];
}
Solution 11 - Iphone
I Borrowed and modified a little bit from the above answer and come up with the following snippet.
- (id)recursivelyFindSuperViewWithClass:(Class)clazz fromView:(id)containedView {
id containingView = [containedView superview];
while (containingView && ![containingView isKindOfClass:[clazz class]]) {
containingView = [containingView superview];
}
return containingView;
}
Passing in class offers the flexibility for traversing and getting views other than UITableView in some other occasions.
Solution 12 - Iphone
My solution to this problem is somewhat similar to other solutions, but uses an elegant for-loop and is short. It should also be future-proof:
- (UITableView *)tableView
{
UIView *view;
for (view = self.superview; ![view isKindOfClass:UITableView.class]; view = view.superview);
return (UITableView *)view;
}
Solution 13 - Iphone
UITableView *tv = (UITableView *) self.superview.superview;
BuyListController *vc = (BuyListController *) tv.dataSource;
Solution 14 - Iphone
Instead of superview, try using ["UItableViewvariable" visibleCells].
I used that in a foreach loops to loop through the cells that the app saw and it worked.
for (UITableView *v in [orderItemTableView visibleCells])//visibleCell is the fix.
{
@try{
[orderItemTableView reloadData];
if ([v isKindOfClass:[UIView class]]) {
ReviewOrderTableViewCell *cell = (ReviewOrderTableViewCell *)v;
if (([[cell deleteRecord] intValue] == 1) || ([[[cell editQuantityText] text] intValue] == 0))
//code here
}
}
}
Works like a charm.
Solution 15 - Iphone
Minimally tested but this non-generic Swift 3 example seems to work:
extension UITableViewCell {
func tableView() -> UITableView? {
var currentView: UIView = self
while let superView = currentView.superview {
if superView is UITableView {
return (superView as! UITableView)
}
currentView = superView
}
return nil
}
}
Solution 16 - Iphone
this code ``UITableView *tblView=[cell superview];` will give you an instance of the UItableview which contains the tabe view cell
Solution 17 - Iphone
I suggest you traverse the view hierarchy this way to find the parent UITableView:
- (UITableView *) findParentTableView:(UITableViewCell *) cell
{
UIView *view = cell;
while ( view && ![view isKindOfClass:[UITableView class]] )
{
#ifdef DEBUG
NSLog( @"%@", [[view class ] description] );
#endif
view = [view superview];
}
return ( (UITableView *) view );
}
Otherwise your code will break when Apple changes the view hierarchy again.
Another answer that also traverses the hierarchy is recursive.
Solution 18 - Iphone
UITableViewCell Internal View Hierarchy Change in iOS 7
Using iOS 6.1 SDK
<UITableViewCell>
| <UITableViewCellContentView>
| | <UILabel>
Using iOS 7 SDK
<UITableViewCell>
| <UITableViewCellScrollView>
| | <UIButton>
| | | <UIImageView>
| | <UITableViewCellContentView>
| | | <UILabel>
The new private UITableViewCellScrollView class is a subclass of UIScrollView and is what allows this interaction:
![enter image description here][1]
[1]: http://i.stack.imgur.com/C2uJa.gif
http://www.curiousfind.com/blog/646 Thank You
Solution 19 - Iphone
You can get it with one line of code.
UITableView *tableView = (UITableView *)[[cell superview] superview];
Solution 20 - Iphone
extension UIView {
func parentTableView() -> UITableView? {
var viewOrNil: UIView? = self
while let view = viewOrNil {
if let tableView = view as? UITableView {
return tableView
}
viewOrNil = view.superview
}
return nil
}
}
Solution 21 - Iphone
from @idris answer I wrote an expansion for UITableViewCell in Swift
extension UITableViewCell {
func relatedTableView() -> UITableView? {
var view = self.superview
while view != nil && !(view is UITableView) {
view = view?.superview
}
guard let tableView = view as? UITableView else { return nil }
return tableView
}