I have a view based NSOutlineView in which the rows contains subviews which have an alpha value of less than 1.
When new rows are inserted or deleted (when the user expands or collapses a row) all of these sub views flash as they seem to temporarily be redrawn with an alpha value of 1.
Does anyone know how to stop this phenomenon ?
I've been looking at this problem four hours, and as so often happens as soon as I post the question here I work out the answer for myself.
Setting up the translucent layers like this solve the issue:
- (void)setup {
// This stops the strange flashing effect when collapsing/expanding rows
self.wantsLayer = YES;
[self.layer setShouldRasterize:YES];
}
- (instancetype)init
{
self = [super init];
if (self) {
[self setup];
}
return self;
}
- (instancetype)initWithCoder:(NSCoder *)coder
{
self = [super initWithCoder:coder];
if (self) {
[self setup];
}
return self;
}
Related
I am trying to customize an NSImageCell for NSTableView using NSArrayController and bindings to change the background of the cell which is selected. So, I created two NSImage images and retain them as normalImage and activeImage in the cell instance, which means I should release these two images when the cell calls its dealloc method. And I override
- (void)drawInteriorWithFrame:(NSRect)cellFrame inView:(NSView *)controlView
and
- (void) setObjectValue:(id) inObject
But I find that when I click any cell in the tableview, the cell's dealloc method is called.
So I put NSLog(#"%#", self); in the dealloc method and - (void)drawInteriorWithFrame:inView: and I find that these two instance are not same.
Can anyone tell me why dealloc is called every time I click any cell? Why are these two instances not the same? What does OS X do when I customize the cell in NSTableView?
BTW: I found that the -init is called only once. Why?
EDIT:
My cell code
#implementation SETableCell {
NSImage *_bgNormal;
NSImage *_bgActive;
NSString *_currentString;
}
- (id)init {
if (self = [super init]) {
NSLog(#"setup: %#", self);
_bgNormal = [[NSImage imageNamed:#"bg_normal"] retain];
_bgActive = [[NSImage imageNamed:#"bg_active"] retain];
}
return self;
}
- (void)dealloc {
// [_bgActive release]; _bgActive = nil;
// [_bgNormal release]; _bgNormal = nil;
// [_currentString release]; _currentString = nil;
NSLog(#"dealloc: %#", self);
[super dealloc];
}
- (void)drawInteriorWithFrame:(NSRect)cellFrame inView:(NSView *)controlView {
NSLog(#"draw: %#", self);
NSPoint point = cellFrame.origin;
NSImage *bgImg = self.isHighlighted ? _bgActive : _bgNormal;
[bgImg drawAtPoint:p fromRect:NSZeroRect operation:NSCompositeSourceOver fraction:1.0];
NSPoint strPoint = cellFrame.origin;
strPoint.x += 30;
strPoint.y += 30;
[_currentString drawAtPoint:strPoint withAttributes:nil];
}
- (void) setObjectValue:(id) inObject {
if (inObject != nil && ![inObject isEqualTo:_currentString]) {
[self setCurrentInfo:inObject];
}
}
- (void)setCurrentInfo:(NSString *)info {
if (_currentString != info) {
[_currentString release];
_currentString = [info copy];
}
}
#end
As a normal recommendation, you should move to ARC as it takes cares of most of the memory management tasks that you do manually, like retain, releases. My answers will assume that you are using manual memory management:
Can anyone tell me why dealloc is called every time I click any cell ?
The only way for this to happen, is if you are releasing or auto-releasing your cell. If you are re-using cells, they shouldn't be deallocated.
Why these tow instance are not same ?
If you are re-using them, the cell that you clicked, and the cell that has been deallocated, they should be different. Pay close attention to both your questions, in one you assume that you are releasing the same cell when you click on it, on the second you are seeing that they are different.
What does Apple do when I custom the cell in NSTableView ?
Apple as a company? Or Apple as in the native frameworks you are using? I am assuming you are going for the second one: a custom cell is just a subclass of something that the NSTableView is expecting, it should behave the same as a normal one plus your custom implementation.
BTW: I found that the init is called only once, and why ?
Based on this, you are probably re-using cells, and only in the beginning they are actually being initialised.
It would be very useful to see some parts of your code:
Your Cell's code
Your NSTableView cell's creation code.
I have to two subviews associated with a view. One is a transparent view that handles a right click, the other a nsview with an nsimageview subview. For some reason the right click works over any part of the superview except the part within the nsimageview. The transparent view is on top of the other view yet the right mouse down event is not firing.
I finally solved it by subclassing the image view and overriding the hit test method to return nil. The full implementation is below :
#implementation TTBaseImageView
- (id)initWithFrame:(NSRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code here.
}
return self;
}
- (void)drawRect:(NSRect)dirtyRect
{
// Drawing code here.
[super drawRect:dirtyRect];
}
-(BOOL)isFlipped
{
return YES;
}
-(BOOL)acceptsFirstResponder
{
return NO;
}
-(BOOL)acceptsFirstMouse:(NSEvent *)theEvent
{
return NO;
}
-(NSView *)hitTest:(NSPoint)aPoint
{
return nil;
}
#end
I am working on an app in which there are five UITextFields in one view controller, the user can fill the text fields they want and when they press a UIButton they'll get a randomized answer on a second view controller via a UILabel.
I got it to work so far, but let's say the user only fills the first two UITextFields and the random answer they get is from a blank, unfilled UITextField.
My question is: how do I make work so that the unfilled UITextFields are not part of the random count? Is this possible?
Here's the code:
FifthViewController.m
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
self.choice1.delegate = self;
self.choice2.delegate = self;
self.choice3.delegate = self;
self.choice4.delegate = self;
self.choice5.delegate = self;
}
- (IBAction)choicebutton:(id)sender {
SixthViewController *SVC = [self.storyboard instantiateViewControllerWithIdentifier:#"SixthViewController"];
SVC.stringFromChoice1 = self.choice1.text;
SVC.stringFromChoice2 = self.choice2.text;
SVC.stringFromChoice3 = self.choice3.text;
SVC.stringFromChoice4 = self.choice4.text;
SVC.stringFromChoice5 = self.choice5.text;
[self presentViewController:SVC animated:YES completion:nil];
}
SixthViewController.m
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
self.choiceAnswers = #[self.stringFromChoice1,
self.stringFromChoice2,
self.stringFromChoice3,
self.stringFromChoice4,
self.stringFromChoice5];
int index = arc4random() % [self.choiceAnswers count];
self.choiceanswer.text = self.choiceAnswers[index];
}
Thanks!
SixthViewController
You can check and see if a string is empty before adding it to self.choiceAnswers:
if(![self.stringFromChoice1 isEqualToString#""]);
{
[self.choiceAnswers addObject:self.stringFromChoice1];
}
Make sure that you are using an NSMutable array for self.choiceAnswers.
I'm trying to write an application that allows the user to drag files from the Finder and drop them onto an NSStatusItem. So far, I've created a custom view that implements the drag and drop interface. When I add this view as a subview of an NSWindow it all works correctly -- the mouse cursor gives appropriate feedback, and when dropped my code gets executed.
However, when I use the same view as an NSStatusItem's view it doesn't behave correctly. The mouse cursor gives appropriate feedback indicating that the file can be dropped, but when I drop the file my drop code never gets executed.
Is there something special I need to do to enable drag and drop with an NSStatusItem?
I finally got around to testing this and it works perfectly, so there's definitely something wrong with your code.
Here's a custom view that allows dragging:
#implementation DragStatusView
- (id)initWithFrame:(NSRect)frame
{
self = [super initWithFrame:frame];
if (self) {
//register for drags
[self registerForDraggedTypes:[NSArray arrayWithObjects: NSFilenamesPboardType, nil]];
}
return self;
}
- (void)drawRect:(NSRect)dirtyRect
{
//the status item will just be a yellow rectangle
[[NSColor yellowColor] set];
NSRectFill([self bounds]);
}
//we want to copy the files
- (NSDragOperation)draggingEntered:(id<NSDraggingInfo>)sender
{
return NSDragOperationCopy;
}
//perform the drag and log the files that are dropped
- (BOOL)performDragOperation:(id <NSDraggingInfo>)sender
{
NSPasteboard *pboard;
NSDragOperation sourceDragMask;
sourceDragMask = [sender draggingSourceOperationMask];
pboard = [sender draggingPasteboard];
if ( [[pboard types] containsObject:NSFilenamesPboardType] ) {
NSArray *files = [pboard propertyListForType:NSFilenamesPboardType];
NSLog(#"Files: %#",files);
}
return YES;
}
#end
Here's how you'd create the status item:
NSStatusItem* item = [[[NSStatusBar systemStatusBar] statusItemWithLength:NSSquareStatusItemLength] retain];
DragStatusView* dragView = [[DragStatusView alloc] initWithFrame:NSMakeRect(0, 0, 24, 24)];
[item setView:dragView];
[dragView release];
Since Yosemite, the method for setting a view on NSStatusItem is deprecated but fortunately there is a much nicer way using the new NSStatusItemButton property on NSStatusItem:
- (void)applicationDidFinishLaunching: (NSNotification *)notification {
NSImage *icon = [NSImage imageNamed:#"iconName"];
//This is the only way to be compatible to all ~30 menu styles (e.g. dark mode) available in Yosemite
[normalImage setTemplate:YES];
statusItem.button.image = normalImage;
// register with an array of types you'd like to accept
[statusItem.button.window registerForDraggedTypes:#[NSFilenamesPboardType]];
statusItem.button.window.delegate = self;
}
- (NSDragOperation)draggingEntered:(id<NSDraggingInfo>)sender {
return NSDragOperationCopy;
}
- (BOOL)performDragOperation:(id<NSDraggingInfo>)sender {
//drag handling logic
}
Please be aware that the button property is only available starting in 10.10 and you might have to keep your old solution if you support 10.9 Mavericks or below.
I want to implement this
1) when user start typing in a textfield a popOver flashes and shows the list of items in a table view in the popover as per the string entered in textfield.
2) Moreover this data should be refreshed with every new letter entered.
kind of predictive search.
Please help me with this and suggest possible ways to implement this.
UISearchDisplayController does most of the heavy lifting for you.
Place a UISearchBar (not a UITextField) in your view, and wire up a UISearchDisplayController to it.
// ProductViewController.h
#property IBOutlet UISearchBar *searchBar;
#property ProductSearchController *searchController;
// ProductViewController.m
- (void) viewDidLoad
{
[super viewDidLoad];
searchBar.placeholder = #"Search products";
searchBar.showsCancelButton = YES;
self.searchController = [[[ProductSearchController alloc]
initWithSearchBar:searchBar
contentsController:self] autorelease];
}
I usually subclass UISearchDisplayController and have it be it's own delegate, searchResultsDataSource and searchResultsDelegate. The latter two manage the result table in the normal manner.
// ProductSearchController.h
#interface ProductSearchController : UISearchDisplayController
<UISearchDisplayDelegate, UITableViewDelegate, UITableViewDataSource>
// ProductSearchController.m
- (id)initWithSearchBar:(UISearchBar *)searchBar
contentsController:(UIViewController *)viewController
{
self = [super initWithSearchBar:searchBar contentsController:viewController];
self.contents = [[NSMutableArray new] autorelease];
self.delegate = self;
self.searchResultsDataSource = self;
self.searchResultsDelegate = self;
return self;
}
Each keypress in the searchbar calls searchDisplayController:shouldReloadTableForSearchString:. A quick search can be implemented directly here.
- (BOOL) searchDisplayController:(UISearchDisplayController*)controller
shouldReloadTableForSearchString:(NSString*)searchString
{
// perform search and update self.contents (on main thread)
return YES;
}
If your search might take some time, do it in the background with NSOperationQueue. In my example, ProductSearchOperation will call showSearchResult: when and if it completes.
// ProductSearchController.h
#property INSOperationQueue *searchQueue;
// ProductSearchController.m
- (BOOL) searchDisplayController:(UISearchDisplayController*)controller
shouldReloadTableForSearchString:(NSString*)searchString
{
if (!searchQueue) {
self.searchQueue = [[NSOperationQueue new] autorelease];
searchQueue.maxConcurrentOperationCount = 1;
}
[searchQueue cancelAllOperations];
NSInvocationOperation *op = [[[ProductSearchOperation alloc]
initWithController:self
searchTerm:searchString] autorelease];
[searchQueue addOperation:op];
return NO;
}
- (void) showSearchResult:(NSMutableArray*)result
{
self.contents = result;
[self.searchResultsTableView
performSelectorOnMainThread:#selector(reloadData)
withObject:nil waitUntilDone:NO];
}
It sounds like you have a pretty good idea of an implementation already. My suggestion would be to present a UITableView in a popover with the search bar at the top, then simply drive the table view's data source using the search term and call reloadData on the table view every time the user types into the box.