Let's Say i loaded 100 rows in a table in awakeFromNib: , Now i want to call a method when the vertical scroller hits the bottom. Could anyone let me know how to handle the event of NSScroller hitting the bottom and calling a method when this happens.
// In awakeFromNib:
self.scrollView = [self.tableView enclosingScrollView];
// Register delegate to the scrollView content View:
// This will send notification whenever scrollView content view visible frame changes.
[NSNotificationCenter.defaultCenter addObserver:self selector:#selector(scrollViewDidScroll:) name:NSViewBoundsDidChangeNotification object:self.scrollView.contentView];
// This Method is called when content view frame changed
- (void)scrollViewDidScroll:(NSNotification *)notification {
NSScrollView *scrollView = self.scrollView;
// Test if bottom of content view is reached.
CGFloat currentPosition = CGRectGetMaxY([scrollView visibleRect]);
CGFloat contentHeight = [self.tableView bounds].size.height - 5;
if (currentPosition > contentHeight - 2.0) {
// YOUR ACTION
}
}
// Remove observer
- (void)dealloc {
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
You can detect a scrollview at bottom by checking if tableView.enclosingScrollView.verticalScroller?.floatValue == 1 since the floatValue of vertical scroller varies between 0 and 1.
Related
Could someone let me know how can I automatically scroll the scrollView when a keyboard-only user tries to navigate between different UI Element in the ScrollView using ‘Tab’ key? When I hit "TAB" key the focus is shifted to different UI element present in the scrollView but it doesn't scroll if the UI Element is not present in the Visible Content View. How can this be achieved. Help would be appreciated. Thanks.
Solution A: Create a subclass of NSWindow and override makeFirstResponder:. makeFirstResponder is called when the first responder changes.
- (BOOL)makeFirstResponder:(NSResponder *)responder {
BOOL madeFirstResponder = [super makeFirstResponder:responder];
if (madeFirstResponder) {
id view = [self firstResponder];
// check if the new first responder is a field editor
if (view && [view isKindOfClass:[NSTextView class]] && [view isFieldEditor])
view = [view delegate]; // the control, usually a NSTextField
if (view && [view isKindOfClass:[NSControl class]] && [view enclosingScrollView]) {
NSRect rect = [view bounds];
rect = NSInsetRect(rect, -10.0, -10.0); // add a margin
[view scrollRectToVisible:rect];
}
}
return madeFirstResponder;
}
Solution B: Create a subclass of NSTextField and other controls and override becomeFirstResponder.
- (BOOL)becomeFirstResponder {
BOOL becameFirstResponder = [super becomeFirstResponder];
if (becameFirstResponder) {
if ([self enclosingScrollView]) {
NSRect rect = [self bounds];
rect = NSInsetRect(rect, -10.0, -10.0); // add a margin
[self scrollRectToVisible:rect];
}
}
return becameFirstResponder;
}
I have an app which I'm updating to auto layout and size classes and I'm getting some weird behaviour with the label on a button.
The button should be a circle and have a label in the centre. I'm implementing my own subclass so I can reuse it.
Here's the storyboard:
and the code for the class which extends UIButton:
- (id)initWithCoder:(NSCoder *)aDecoder
{
self = [super initWithCoder:aDecoder];
if (self) {
[self setBackgroundImage:[UIImage imageNamed:#"selected-green"] forState:UIControlStateHighlighted ];
self.layer.borderColor = [UIColor tlbWhiteColor].CGColor;
self.layer.borderWidth = 10;
}
return self;
}
-(void) layoutSubviews {
self.layer.cornerRadius = self.frame.size.width / 2;
}
With this the appears as expected but there is no label. On debugging I see that the frame of the label has 0 height and width. So I extended layoutSubviews:
-(void) layoutSubviews {
self.layer.cornerRadius = self.frame.size.width / 2;
if (self.titleLabel.frame.size.width == 0) {
[self.titleLabel sizeToFit];
[self setNeedsLayout];
[self layoutIfNeeded];
}
}
The label then appears, but it's in the wrong place:
The only extra info I can offer is that in Reveal the button has weird height and width constraints added:
The titleInsets are all at 0.
Help hugely appreciated.
I don't think you need the layoutSubviews override. I think it's a hack and it's hiding your real issue.
What are the constraints on the 'Go' label? How are you centering it in the UIButton? Also what is the height constraint on the label?
My suggestion would be to put both the UIButton and the Go label inside a container view and centre the label inside the container view. The container view should have the same height and width as the UIButton inside it.
Also are you changing the frames of the views programmatically somewhere in the app? Those weird constraints you talk about in reveal point to that.
As per your requirements:
- (void)viewDidLoad {
[super viewDidLoad];
view_1.layer.cornerRadius = 10; //view_1 is white color
view_1.layer.masksToBounds = YES;
view_2.layer.cornerRadius = _view_2.frame.size.width/2;//view_2 is green color
view_2.layer.masksToBounds = YES;
}
output
Ok, this was a real school boy error.
When the docs said 'The implementation of this method is empty before iOS 6' I for some reason took this to mean there's no need to call super on layoutSubviews.
So the fix was:
-(void) layoutSubviews {
[super layoutSubviews]; // <<<<< THIS WAS MISSING
self.layer.cornerRadius = self.frame.size.width / 2;
self.layer.masksToBounds = YES;
}
After switching to iOS8, I'm getting weird behavior when I move views during a keyboard transition. Can anyone explain what's going on?
Here's a minimal example to demonstrate the problem. I have a simple view with a UITextField and a UIButton. The function nudgeUp moves the text field and the button up by 10 points. It is triggered either by the buttonPressed callback, or the keyboardWillShow callback.
When I tap the button, the code works as expected: buttonPressed calls nudgeUp and the button and text field jump up by 10 points.
When I tap the text field, keyboardWillShow calls nudgeUp, but the behaviour is very different. The button and text field immediately jump down by 10 points, and then slide back up to their original position as the keyboard shows itself.
Why is this happening? How can I regain control of animations during keyboard presentation in iOS8?
#import "ViewController.h"
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(keyboardWillShow:)
name:UIKeyboardWillShowNotification
object:nil];
}
- (void)keyboardWillShow:(NSNotification *)notification
{
// Called when the keyboard appears.
[self nudgeUp];
}
- (IBAction)buttonPressed:(id)sender {
[self nudgeUp];
}
- (void)nudgeUp
{
CGRect newTextFieldFrame = self.textField.frame;
newTextFieldFrame.origin.y -= 10;
self.textField.frame = newTextFieldFrame;
CGRect newButtonFrame = self.button.frame;
newButtonFrame.origin.y -= 10;
self.button.frame = newButtonFrame;
}
#end
It's AutoLayout. Something changed in iOS8 and you can't just change frame or center points anymore if you have AutoLayout enabled. You have to create an outlet(s) of your constraint (vertical space) and update it accordingly instead of changing frame position. Constraints are like any other ui control and can have an outlet. Constraint change can be animated.
Example:
[UIView animateWithDuration:[notification.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue] delay:0 options:[[[notification userInfo] objectForKey:UIKeyboardAnimationCurveUserInfoKey] integerValue] animations:^{
self.bottomSpaceConstraint.constant = adjustmentedValue;
[self.view layoutIfNeeded];
} completion:^(BOOL finished) {
}];
You should use UIKeyboardDidShowNotification (you're using will version) and everything will work as you expect:
- (void)viewDidLoad {
[super viewDidLoad];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(keyboardDidShow:)
name:UIKeyboardDidShowNotification
object:nil];
}
- (void)keyboardDidShow:(NSNotification *)notification
{
// Called when the keyboard finished showing up
[self nudgeUp];
}
The explanation is that with UIKeyboardWillShowNotification you are changing the frames too early. After your changes the system will relayout everything to accomodate the keyboard and your changes won't have any effect.
Also, I recommend you to switch to autolayout and forget about frames.
Try using the UIKeyboardWillShowNotification userInfo to give you the frame of the keyboard. Then move the onscreen elements based on that.
i created a image view
for(int i=0; i<pcount; i++)
{
int x = rand() % 350;
int y = rand() % 350;
NSRect rect = NSMakeRect((x+10),(y+10), 200, 200);
//NSImageView *imageView
imageView1 = [[NSImageView alloc]initWithFrame:rect];
[imageView1 setTag:i];
// imageView = [[NSImageView alloc]initWithFrame:rect];
// [imageView1 rotateByAngle:rand() % 150];
[imageView1 setImageScaling:NSScaleToFit];
[imageView1 canBecomeKeyView];
NSImage *theImage = [[NSImage alloc]initWithContentsOfURL:(NSURL*)[patharray objectAtIndex:(i)]];
[imageView1 setImage:theImage];
[[imageView1 cell] setHighlighted:YES];
[[layoutCustom view] addSubview:imageView1 positioned:NSWindowMovedEventType relativeTo:nil];}
now how can select each image view by mouse click ? thanks in advance.
I'm assuming here that you have your reasons for not using existing collection views. So from what I read in your code you have layoutCustom.view, which contains a bunch of NSImageViews. Here are two options:
In your layoutCustom object implement the mouseDown: (or mouseUp: or both). Take the event location convert it view coordinates and look for any subview for which CGRectContainsPoint(subview.frame, mouseDownPoint) return YES. You should select that view.
Subclass NSImageView and implement mouseDown: (or mouseUp: or both). On mouseDown: simply set a "selected" flag. Either the view can draw something itself when selected or the layoutCustom object can observe the property and draw the selection accordingly.
I would prefer option 1 because it simpler, requires fewer classes and fewer interactions between objects.
// Option 1 (in layoutCustom class)
- (void) mouseDown:(NSEvent*)theEvent {
CGPoint mouseDownPoint = [self convertPoint:theEvent.locationInWindow fromView:nil];
for (NSView *view in self.subviews) {
if (CGRectContainsPoint(view.frame, mouseDownPoint)) {
// Do something to remember the selection.
// Draw the selection in drawRect:
[self setNeedsDisplay:YES];
}
}
}
// Option 2 (in Custom subclass of NSImage)
- (void) mouseDown:(NSEvent*)theEvent {
self.selected = !self.selected;
}
// Option 2 (in layoutCustom class)
- (void) addSubview:(NSView*)view positioned:(NSWindowOrderingMode)place relativeTo:(NSView*)otherView {
[super addSubview:view positioned:place relativeTo:otherView];
[self startObservingSubview:view];
}
- (void) willRemoveSubview:(NSView*)view {
[self stopObservingSubview:view];
}
- (void) startObservingSubview:(NSView*)view {
// Register your KVO here
// You MUST implement observeValueForKeyPath:ofObject:change:context:
}
- (void) stopObservingSubview:(NSView*)view {
// Remove your KVO here
}
I've got a better idea: Instead of fighting with converting mouse clicks in a view to coordinates and then figuring out how to map it to the right subview or sub-image, why not have one big (or scrolling?) view and then add your images as giant "NSButton" objects (set to custom type), where the button images can be the images you want to add.
As for how to select each image? You can either subclass "NSButton" and keep track of some custom data within it, or you can use a "tag" to figure out which button was pressed in your "IBAction" method and then decide what to do with it.
Another approach might be to embed your images into NSTableView cells...
#import "LoginScreen.h"
#define kTabBarHeight 1
#define kKeyboardAnimationDuration 0.3
#implementation LoginScreen
#synthesize userName,password,loginButton,scrollView;
BOOL keyboardIsShown;
// The designated initializer. Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad.
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization.
}
return self;
}
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
[super viewDidLoad];
// register for keyboard notifications
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(keyboardWillShow:)
name:UIKeyboardWillShowNotification
object:self.view.window];
// register for keyboard notifications
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(keyboardWillHide:)
name:UIKeyboardWillHideNotification
object:self.view.window];
keyboardIsShown = NO;
//make contentSize bigger than your scrollSize (you will need to figure out for your own use case)
// CGSize scrollContentSize = CGSizeMake(1024,700 );
// [scrollView setContentSize : scrollContentSize];
self.scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
}
- (void)keyboardWillHide:(NSNotification *)n
{
NSDictionary* userInfo = [n userInfo];
// get the size of the keyboard
NSValue* boundsValue = [userInfo objectForKey:UIKeyboardBoundsUserInfoKey];
CGSize keyboardSize = [boundsValue CGRectValue].size;
// resize the scrollview
CGRect viewFrame = self.scrollView.frame;
// I'm also subtracting a constant kTabBarHeight because my UIScrollView was offset by the UITabBar so really only the portion of the keyboard that is leftover pass the UITabBar is obscuring my UIScrollView.
viewFrame.size.height += (keyboardSize.height - kTabBarHeight);
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationBeginsFromCurrentState:YES];
// The kKeyboardAnimationDuration I am using is 0.3
[UIView setAnimationDuration:kKeyboardAnimationDuration];
[self.scrollView setFrame:viewFrame];
[UIView commitAnimations];
keyboardIsShown = NO;
}
- (void)keyboardWillShow:(NSNotification *)n
{
// This is an ivar I'm using to ensure that we do not do the frame size adjustment on the UIScrollView if the keyboard is already shown. This can happen if the user, after fixing editing a UITextField, scrolls the resized UIScrollView to another UITextField and attempts to edit the next UITextField. If we were to resize the UIScrollView again, it would be disastrous. NOTE: The keyboard notification will fire even when the keyboard is already shown.
if (keyboardIsShown) {
return;
}
NSDictionary* userInfo = [n userInfo];
// get the size of the keyboard
NSValue* boundsValue = [userInfo objectForKey:UIKeyboardBoundsUserInfoKey];
CGSize keyboardSize = [boundsValue CGRectValue].size;
// resize the noteView
CGRect viewFrame = self.scrollView.frame;
// I'm also subtracting a constant kTabBarHeight because my UIScrollView was offset by the UITabBar so really only the portion of the keyboard that is leftover pass the UITabBar is obscuring my UIScrollView.
viewFrame.size.height -= (keyboardSize.height - kTabBarHeight);
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationBeginsFromCurrentState:YES];
// The kKeyboardAnimationDuration I am using is 0.3
[UIView setAnimationDuration:kKeyboardAnimationDuration];
[self.scrollView setFrame:viewFrame];
[UIView commitAnimations];
keyboardIsShown = YES;
}
- (IBAction) loginButton: (id) sender{
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
// Overriden to allow any orientation.
return YES;
}
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc. that aren't in use.
}
- (void)viewDidUnload {
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
// unregister for keyboard notifications while not visible.
[[NSNotificationCenter defaultCenter] removeObserver:self
name:UIKeyboardWillShowNotification
object:nil];
// unregister for keyboard notifications while not visible.
[[NSNotificationCenter defaultCenter] removeObserver:self
name:UIKeyboardWillHideNotification
object:nil];
}
- (void)dealloc {
[scrollView release];
[super dealloc];
}
#end
Can anybody tell me whats wrong in code below. The original view doesn't move up even though i am subtracting the keyboards height to the frame heights.
The scrollView doesn't move up when keyboard pops in? Am I missing some code here.
Well, the problem is that you're not telling your code where your text field is to begin with, so it has no idea where it needs to scroll from. You probably thought that your self.scrollView.frame does it, but that only tells the code the size of your ScrollView, not that it needs to scroll or should scroll. Here's what I did to get mine to work.
Look at the connections for one of your text fields. Drag and drop from the "Did Begin Editing" and "Did End Editing" into your .h file to create IBAction function declarations. Xcode is going to put functions into the .m, but replace them with these:
//even though these functions don't reference the IBAction that we placed for the
"DidBeginEditing" sender for a text field, it will still call these functions.
We need to let the code know what text field we just touched so we can go through
the functions that reset the view size if the text field is under the keyboard.
- (void)textFieldDidBeginEditing:(UITextField *)textField
{
currentTextField = textField;
}
- (void)textFieldDidEndEditing:(UITextField *)textField
{
currentTextField = nil;
}
That reminds me, you'll need to declare currentTextField as a UITextField * in the .m:
#interface ThirdView : UIViewController{
UITextField *currentTextField;
BOOL keyboardIsShown;
}
My viewDidLoad, keyBoardWasShown, etc are a bit different from yours, but I'll just put them all here so you can see how I got it to work:
//This is code you actually add to get the view to scroll.
You should first connect an outlet from the ScrollView to the .h file so these
functions become available.
- (void)viewDidLoad {
//standard screen size is 320 X 460
// ---set the viewable frame of the scroll view---
// scrollView.frame = CGRectMake(0, 0, 320, 460);
//---set the content size of the scroll view---
// [scrollView setContentSize:CGSizeMake(320, 615)];
//the status bar is 20 pixels tall
//the navigation bar is 44 pixels tall
//---set the viewable frame of the scroll view---
//Note: for some reason, the origin (0,44) doesn't take into account the status bar, but it works anyway. However, the height of the scroll view does take it into account. Wierd, but whatever. So you have to make y1 = 44, and y2 = 460-44-20.
scrollView.frame = CGRectMake(0, 44, 320, 416);
//---set the content size of the scroll view---
[scrollView setContentSize:CGSizeMake(320, 571)];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(keyboardWasShown:)
name:UIKeyboardDidShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(keyboardWillBeHidden:)
name:UIKeyboardWillHideNotification object:nil];
[super viewDidLoad];
}
- (void)viewDidUnload
{
[self setPrincipal_Amt:nil];
[self setAPR:nil];
[self setYears:nil];
[self setScrollView:nil];
[super viewDidUnload];
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
// Called when the UIKeyboardDidShowNotification is sent.
- (void)keyboardWasShown:(NSNotification*)aNotification
{
if(keyboardIsShown)
return;
NSDictionary* info = [aNotification userInfo];
CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbSize.height, 0.0);
scrollView.contentInset = contentInsets;
scrollView.scrollIndicatorInsets = contentInsets;
// If active text field is hidden by keyboard, scroll it so it's visible
Notice that we've got to add 64 pixels to the keyboard height because the CGRect has
no idea that you have the status bar shown and a navigation bar within your view, so
you have to manually add it in.
CGRect aRect = self.view.frame;
aRect.size.height -= (kbSize.height + 64);
if (!CGRectContainsPoint(aRect, currentTextField.frame.origin) )
{
CGPoint scrollPoint = CGPointMake(0.0, currentTextField.frame.origin.y-kbSize.height + 64);
[scrollView setContentOffset:scrollPoint animated:YES];
}
keyboardIsShown = YES;
}
// Called when the UIKeyboardWillHideNotification is sent
- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{
UIEdgeInsets contentInsets = UIEdgeInsetsZero;
scrollView.contentInset = contentInsets;
scrollView.scrollIndicatorInsets = contentInsets;
keyboardIsShown = NO;
}
//
I hope that helps...even though you did post this a while ago :) It took me a while to get it to work too. Very frustrating.