I'm having issues trying to handle the events from a Subview of my Parent View, right now I have a UIViewController that has a a subView another UIViewController, in this subView I have a paging scrollView, I want to fire a method on the parent view when I swipe the subView scroll View, do you have any suggestions on how can I develop this?, thanks
You could make the parent view a delegate of the subview.
Add this to the SubView.h:
// add
#protocol SubViewClassNameDelegate
#required
- (void)triggerMethodFromSubView:(NSString *)value;
#end
//
#interface SubViewClassName : UIView
// add
#property (nonatomic, assign) id<SubViewClassNameDelegate> delegate
//
#end
Then in your parent view class, add this to ParentView.h:
#interface ParentViewClassName : UIView /* add -> */ <SubViewClassNameDelegate>
and this in ParentView.m right after the instantiation of your subview:
[mySubView setDelegate:self];
Finally, add your delegate trigger method somewhere in ParentView.m:
- (void)triggerMethodFromSubView:(NSString *)value {
// do stuff
}
Now, you can call [self.delegate triggerMethodFromSubView:#"Hello World"] anywhere in your subview class, and it will tell the parent view to call your delegated method.
If you need additional info, here's a helpful tutorial: http://www.alexefish.com/post/522641eb31fa2a0015000002
Related
I'm trying to find a solution that allows me to get keydown events in a view controller.
I do not believe a view controller is part of the responder chain by default.
I would appreciate a sample of how to go about this. I have had trouble finding documentation I can understand on how to add the VC to the responder chain and get the events.
Thanks.
Miek
You can implement something like this:
-(void) globalKeyDown: (NSNotification *) notification
method in your controller class, and then just add the observer in awakeFromNib...or loadView method of your controller
- (void)awakeFromNib
{
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(globalKeyDown:)
name:#"my_keyEvent"
object:nil];
}
in your view class
-(void)keyDown:(NSEvent *)theEvent
{
[[NSNotificationCenter defaultCenter] postNotificationName:#"my_keyEvent"
object:theEvent
userInfo:#{#"sender":self}];
}
NSViewController doesn't have a default way to do this. However, you can achieve this through subclassing NSView. Here is the basic idea:
If you create a view subclass, you can set your view controller as a delegate and create a delegate method that handles events.
You can declare a delegate protocol at the start of your view header.
Import your view header in the view controller header. Declare the view controller as implementing the protocol.
In your view keyDown send the event to the delegate.
Another way is to post NSNotifications in your keyDown and observe and handle the notifications in your view controller. Other ways also exist.
NSView Subclass with Delegate method explained
Here is the delegation example with an NSView subclass which declares a protocol in its header with one required method, an IBOutlet id property that conforms to the protocol. The NSView subclass calls this method to its delegate whenever it wants to. If the delegate is nil, that's fine in Cocoa. Also note, tangentially, I have added IB_Designable and IBInspectable to the view's color properties. This allows setting them in IB and requires the 10.10 SDK.
The app delegate has imported the NSView subclass in the AppDelegate.m implementation file and adopted the protocol in the AppDelegate class extension at the top of the .m file. In the #implementation section it also implements the method.
Also note in IB, I added an NSView to the window, then set its class to the custom NSView subclass in the inspector. Finally, I set its eventDelegate IBOutlet to the AppDelegate proxy in IB.
Custom NSView subclass interface
#import <Cocoa/Cocoa.h>
#protocol EventDelegatingViewDelegate <NSObject>
- (void)view:(NSView *)aView didHandleEvent:(NSEvent *)anEvent;
#end
IB_DESIGNABLE
#interface EventDelegatingView : NSView
#property IBOutlet id<EventDelegatingViewDelegate> eventDelegate;
#property IBInspectable NSColor *fillColor;
#property IBInspectable NSColor *strokeColor;
#end
Custom NSView subclass implementation
#import "EventDelegatingView.h"
#implementation EventDelegatingView
- (BOOL)acceptsFirstMouse:(NSEvent *)theEvent {return YES;}
// The following two methods allow a view to accept key input events. (literally they say, YES, please send me those events if I'm the center of attention.)
- (BOOL)acceptsFirstResponder {return YES;}
- (BOOL)canBecomeKeyView {return YES;}
- (void)drawRect:(NSRect)dirtyRect {
[super drawRect:dirtyRect];
[self.fillColor set];
NSRectFill(self.bounds);
[self.strokeColor set];
NSFrameRect(self.bounds);
}
// Notice these don't do anything but call the eventDelegate. I could do whatever here, but I didn't.
// The NICE thing about delgation is, the originating object stays in control of it sends to its delegate.
// However, true to the meaning of the word 'delegate', once you pass something to the delegate, you have delegated some decision making power to that delegate object and no longer have any control (if you did, you might have a bad code smell in terms of the delegation design pattern.)
- (void)mouseDown:(NSEvent *)theEvent
{
[self.eventDelegate view:self didHandleEvent:theEvent];
}
- (void)keyDown:(NSEvent *)theEvent
{
[self.eventDelegate view:self didHandleEvent:theEvent];
}
#end
App Delegate (and eventDelegate!) implementation
#import "AppDelegate.h"
// Import the view class and if there were other files that implement any protocol
#import "EventDelegatingView.h"
// Declare protocol conformance (or more accurately, not only import that protocol interface, but say you're going to implement it so the compiler can nag you if you don't)
#interface AppDelegate ()<EventDelegatingViewDelegate>
#property (weak) IBOutlet NSWindow *window;
// For the simplest demo app we don't even need this property.
#property IBOutlet EventDelegatingView *eventDelegatingView;
#end
#implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
// Insert code here to initialize your application
}
- (void)applicationWillTerminate:(NSNotification *)aNotification {
// Insert code here to tear down your application
}
// It's all right here. Receive a reference to a view and a reference to an event, then do as you like with them.
#pragma mark - EventDelegatingViewDelegate
- (void)view:(NSView *)aView didHandleEvent:(NSEvent *)anEvent
{
NSString *interestingEventNote;
switch (anEvent.type) {
case NSKeyDown:
case NSKeyUp:
{
// For simplicity we won't try to figure out the modifier keys here.
interestingEventNote = [NSString stringWithFormat:#"%# key was pressed.", anEvent.charactersIgnoringModifiers];
}
break;
case NSLeftMouseDown:
{
interestingEventNote = [NSString stringWithFormat:#"Left mouse down at point %# in window", NSStringFromPoint(anEvent.locationInWindow)];
}
break;
default:
break;
}
NSLog(#"%# %# aView=%#\n note=%#", self, NSStringFromSelector(_cmd), aView, interestingEventNote?interestingEventNote:#"Nothing worth noting");
}
#end
And that's it for the power of delegation. Basically it's callbacks of sorts and is a great way to build a class to enable it to defer something elsewhere as wanted. Moving some business logic to the right place in a fairly lazy and open and loosely coupled way.
NOTE: My code example shows using the app delegate. But the principal is the same. A view controller is little more than a delegate and you can add as much or as little as you like.
In your NSWidow (or NSWindowController) class implementation set your view controller as the first responder:
[self makeFirstResponder:yourViewControllerInstance];
You must, of course, make your NSViewController class return YES to the acceptsFirstResponder message.
I have a UITableViewController and I need to resize the table vertically.
I can't use a UIViewController with a table inside.
There is a method?
Thanks!
This is only possible if your UITableViewController view is manually added to another superview. However, if you are planning to use the table view in a navigation controller or as a modal sheet you do not have control over the table view's size.
To have full control over the table view size:
Make you own subclass of UIViewController with UITableView outlet and a resource file.
Place a UITableView on top of its content view and resize it accordingly.
Make your view controller implement UITableViewDataSource and UITableViewDelegate protocols.
Connect outlets.
Instead of using a UITableViewController, it may be easier just to use a standard UIViewController, with a UITableView property.
E.g.:
#interface ContentsPopover : UIViewController <UITableViewDelegate, UITableViewDataSource>
//...
#property (nonatomic, strong) UITableView *theTableView;
//...
#end
That way, inside your UIViewController you can have the following code (possibly in viewDidLoad):
theTableView = [[UITableView alloc] initWithFrame:/*...*/ style:UITableViewStylePlain];
theTableView.delegate = self;
theTableView.dataSource = self;
theTableView.scrollEnabled = YES;
[self.view addSubview:theTableView];
// You can now change theTableView's frame property as needed
This is handy for when a UITableViewController wasn't quite what you're looking for.
I have a UIView that presents a tableView in a Popover. This tableView then presents another tableView with selectable data. Could someone please explain to me how rouse delegation to get the selected data all the way back to the UIView? I initialize the 2nd tableView and set it's delegate to 'self' when I present the popover. But when I actually do to use the delegate in the 2nd tableView, it is set to null.
That would be something like:
TopMostView.h
#protocol ParentViewDelegate
-(void) operateOnData:(NSObject *)data;
#end
#interface TopMostSubview <ParentViewDelegate>
...
in TopMostView.m
-(void)crateSubview {
... create subview stuff
subview.delegate = self;
...
}
Then in each of the subviews have something like:
#property (weak, nonatomic) id<ParentViewDelegate> delegate;
Whenever you wish to pass data to the superview, you use the operateonData: selector.
I have a view controller which contains a UISearchBar
#interface TradeFindHeaderViewController_iPhone : UIViewController {
UISearchBar *searchBar;
}
#pragma mark - Properties
#property (nonatomic, retain) IBOutlet UISearchBar *searchBar;
#pragma mark - Methods
-(void) configureSearchBar;
#end
This controller is then initialized and stored in a property of another controller.
#interface TradeFindViewController_iPhone : TradeFindViewController<UISearchBarDelegate> {
TradeFindHeaderViewController_iPhone *_headerController;
}
#pragma mark - Properties
#property (nonatomic, retain) TradeFindHeaderViewController_iPhone *headerController;
#end
I want this TradeFindViewController_iPhone to receive the UISearchBar delegate events so I assign it's delegate
-(void)configureTableHeader{
self.headerController=[[TradeFindHeaderViewController_iPhone alloc]initWithNibName:#"TradeFindHeaderView_iPhone" bundle: nil];
self.headerController.searchBar.delegate=self;
self.tableView.tableHeaderView=self.headerController.view;
}
However, the UISearchBar delegate events are not being called. Have I assigned the delegate properly given the UISearchBar is in the contained view?
I would probably implement a multi-level delegate system. Your TradeFindHeaderViewController_iPhone class would register as the delegate for the UISearchBar, and would then call a delegate method in your TradeFindViewController_iPhone class.
This solution helps to keep the whole design very modular, and also prevents things breaking (changing the name of objects) across classes.
This should solve your issue with the delegate methods not being called.
Hope this was of some help.
Josh
So I have an app, and in the app there is a tableView, I have a uinavigationbarbutton that presents a modal viewController. When the user hits a go button in the modal interface, I want it dismiss the modal view and get some of the information in the modal view. I will than put that info in the tableView. To do this, I wrote a custom delegate, but it doesn’t work. I included my code below. Thanks for any help.
TrackerMainViewController.h //the tableView
#import "NewItemViewController.h"
#interface TrackerMainViewController : UITableViewController <UITableViewDelegate, DetailDelegate>
TrackerMainViewController.m
-(void)finishedAddingFoodItemFromDetail:(NSDate *)date whatWasEaten:(NSString *)whatFood whichMeal:(NSString *)meal {
NSLog(#"in delegate method here");
[self.tableView reloadData];
[self dismissModalViewControllerAnimated:YES];
}
NewItemViewController.h // the modal view
#protocol DetailDelegate <NSObject>
-(void)finishedAddingFoodItemFromDetail:(NSDate *)date whatWasEaten:(NSString *)whatFood whichMeal:(NSString *)meal;
#end
#interface NewItemViewController : UIViewController {
id <DetailDelegate> _delegate;
}
#property (nonatomic, retain) id <DetailDelegate> delegate;
#end
NewItemViewController.h
#implementation NewItemViewController
#synthesize delegate = _delegate;
//the go button in the modal view
- (IBAction)Go:(id)sender {
[self.delegate finishedAddingFoodItemFromDetail:[NSDate date] whatWasEaten:#"chicken" whichMeal:#"breakfast"];
}
I put a log in both the go button and in the implementation of the delegate in the tableview, but only the go log is being called.
Thanks
In the code you posted, you dont set the delegate. You need to set it similar to this detailView.delegate = self, otherwise it is nil. You can send messages to a nil-object without any warning and error, nothing will happen.