I need to know if a point is inside at lease one of the views in a given set of views. For that, I used UIView's pointInView method, but it always returns NO. As an act of despair, I checked if the view's center point is inside the view and it also returned NO. This is the code I've used for that:
BOOL wasPointFound = NO;
NSArray *views = [view subviews];
for (UIView *curView in views)
{
if ([curView pointInside:curView.center withEvent:nil])
{
wasPointFound = YES;
break;
}
}
if (!wasPointFound)
NSLog(#"NO");
else
NSLog(#"YES");
Can anybody please tell me what I'm doing wrong?
Thanks,
PointInView is used to check if touch event is inside a view, that means that it is related to the window and not to the view. Taking curView.center is relative to the view therefore there is a good chance that using it will return false.
Try using CGPointMake(curView.frame.origin.x+curView.center.x,curView.frame.origin.y+curView.center.y)
This should return YES
Related
I have made a view in the application that shows a UITableView. It will be full of results (obviously) almost all the time, however when it does not have any results I want to show another view that inform the user about how he/she could populate the table.
I want to design that view in the interfacebuilder. I will have to check in the code whether the datasource is empty or not to toggle between the two different nibs. How do I instantiate and configure a view made in Interfacebuilder?
The easies way to do this is by adding the view in xib normally and make it visible
Design your both views, the table view and the other view, give the tableView a tag of 111 for example and give the otherview another tag 222 for example
Now in viewDidLoad
Get both the views
UIView *noDataView = [self.view viewWithTag:222];
UITableView *tableView = [self.view viewWithTag:111];
//Hide both of them or only the noDataView until you know if you have data from the dataSource or not
Check for your data source
//hasElements do you have any element to show?
if(hasElements)
{
noDatView.hidden = YES;
tableView.hidden = NO;
}
else
{
noDatView.hidden = NO;
tableView.hidden = YES;
}
You can load nib file based on condition.You can write category as follows:
self.view = (UIView *)[self loadNib:#"SecondView" inPlaceholder:self.view];
- (UIView *)viewFromNib:(NSString *)nibName
{
NSArray *xib = [[NSBundle mainBundle] loadNibNamed:nibName owner:self options:nil];
for (id view in xib) { // have to iterate; index varies
if ([view isKindOfClass:[UIView class]]) return view;
}
return nil;
}
- (UIView *)loadNib:(NSString *)nibName inPlaceholder:(UIView *)placeholder
{
UIView *nibView = [self viewFromNib:nibName];
[nibView setFrame:placeholder.frame];
self.view = nibView;
//[self.view insertSubview:nibView aboveSubview:placeholder];
//[placeholder removeFromSuperview];
return nibView;
}
The other answers give you possible technical solutions but I would propose that if you are using the standard Apple design guidelines, you probably don't even need to worry about it. For instance, somewhere on your screen you should have a bar button item with the identifier "Add" (which shows the plus icon). Then rather than giving a long (often poorly localised) description of how to add items, just have a header for an empty section which says "No items" replacing items with whatever pluralised noun is appropriate for your table's items. For example, for an Archery related app I am working on:
Notice how the Edit button is currently disabled too, thus no explanation is needed as the only thing they can do at this point is tap the Add button (screenshots on the Appstore will have shown them what they can expect to see after this point).
I have an app which I add a subview to (and remove the same subview based on user interactions). I am looking for a way to check whether the subview is present or not at any given time.
For example:
In the current view (UIView *viewA) I add a subview (UIView *viewB). I then want a way of checking whether viewB is being displayed at any given time.
Sorry if this isn't very clear, it's quite hard to describe.
an UIView stores its superview and is accessible with the superview-property just try
if([viewB superview]!=nil)
NSLog(#"visible");
else
NSLog(#"not visible");
But the better approach is to use the hidden-property of UIView
I went through the same issue and consulted Apple Documentation and came up with this elegant solution:
if([self.childView isDescendantOfView:self.parentView])
{
// The childView is contained in the parentView.
}
I updated to Swift4, Thanks a lot to #Shinnyx and #thomas.
if viewB.superview != nil{
print("visible")
}
else{
print("not visible")
}
if selfView.isDescendant(of: self.parentView) {
print("visible")
}
else{
print("not visible")
}
func isDescendant(of: UIView)
Returns a Boolean value indicating whether the receiver is a subview of a given view or identical to that view.
Here's a method I put in the appDelegate so that I can display the entire subview hierarchy from any point.
// useful debugging method - send it a view and it will log all subviews
// can be called from the debugger
- (void) viewAllSubviews:(UIView *) topView Indent:(NSString *) indent {
for (UIView * theView in [topView subviews]){
NSLog(#"%#%#", indent, theView);
if ([theView subviews] != nil)
[self viewAllSubviews:theView Indent: [NSString stringWithFormat:#"%# ",indent]];
}
}
call it with a string with one character and it will indent for you. (i.e. [appDelegate viewAllSubviews:self.view Indent:#" "];)
I find it useful to clear the debug pane first, then call this from the debugger, and copy it into a text editor like BBEdit that will show the indents.
You can call it using the mainWindow's view and see everything on your screen.
I'm using TTLauncherView as a sort of home screen for my app and I only have one page's worth of icons. How can I make it so the TTLauncherView won't let you drag icons to "the next page"? I want to set a maximum number of pages (in this case one.)
(EDIT: long story short, I subclassed beginEditing, see the answer below.)
I see where why it adds an extra page when beginEditing is called, but I don't want to edit the framework code. (That makes it hard to update to newer versions.) I'd also prefer not to subclass and override that one method, if I have to rely on how it's implemented. (I'm not against subclassing or adding a category if it's clean.)
I tried setting scrollView.scrollEnabled to NO in the callback method launcherViewDidBeginEditing in my TTLauncherViewDelegate, but that doesn't work while it's in editing mode and I don't know why.
I tried adding a blocker UIView to the scrollview to intercept the touch events by setting userInteractionEnabled=NO, which works OK. I still have to disable the dragging of TTLauncherItems to the next page somehow.
I also tried setting the contentSize of the scrollview to it's bounds in launcherViewDidBeginEditing, but that didn't seem to work either.
Is there a better way?
Tried to block gestures:
- (void)setLauncherViewScrollEnabled:(BOOL)scrollEnabled {
if (scrollEnabled) {
[self.scrollViewTouchInterceptor removeFromSuperview];
self.scrollViewTouchInterceptor = nil;
} else {
// iter through the kids to get the scrollview, put a gesturerecognizer view in front of it
UIScrollView *scrollView = [launcherView scrollViewSubview];
self.scrollViewTouchInterceptor = [UIView viewWithFrame:scrollView.bounds]; // property retains it
UIView *blocker = self.scrollViewTouchInterceptor;
[scrollView addSubview:scrollViewTouchInterceptor];
[scrollView sendSubviewToBack:scrollViewTouchInterceptor];
scrollViewTouchInterceptor.userInteractionEnabled = NO;
}
}
For reference: TTLauncherView.m:
- (void)beginEditing {
_editing = YES;
_scrollView.delaysContentTouches = YES;
UIView* prompt = [self viewWithTag:kPromptTag];
[prompt removeFromSuperview];
for (NSArray* buttonPage in _buttons) {
for (TTLauncherButton* button in buttonPage) {
button.editing = YES;
[button.closeButton addTarget:self action:#selector(closeButtonTouchedUpInside:)
forControlEvents:UIControlEventTouchUpInside];
}
}
// Add a page at the end
[_pages addObject:[NSMutableArray array]];
[_buttons addObject:[NSMutableArray array]];
[self updateContentSize:_pages.count];
[self wobble];
if ([_delegate respondsToSelector:#selector(launcherViewDidBeginEditing:)]) {
[_delegate launcherViewDidBeginEditing:self];
}
}
I think overriding beginEditing in TTLauncherView is your best bet. Since you'd only really be touching one method (and only a few lines in that method), upgrading it when the time comes shouldn't be too bad. Since that method explicitly adds the extra page, I'm not sure how you'd get around it w/o editing that specific piece of code
As Andrew Flynn suggested in his answer, I was able to make it work by subclassing and overriding the beginEditing method to remove the extra page TTLauncherView adds when it goes into editing mode.
One problem I'm having is I can't figure out how to remove the warning I get for calling the (private) method updateContentSize on my subclass. I tried casting it to id, but that didn't remove the warning. Is it possible?
edit: I was able to remove the warning by using performSelector to send the message to the private class. (I had previously create a category method performSelector:withInt that wraps NSInvocation so that I can pass primitives via performSelector methods, which makes this very convenient.)
// MyLauncherView.h
#interface MyLauncherView : TTLauncherView {
NSInteger _maxPages;
}
#property (nonatomic) NSInteger maxPages;
#end
// MyLauncherView.m
#implementation MyLauncherView
#synthesize maxPages = _maxPages;
- (void)beginEditing {
[super beginEditing];
// ignore unset or negative number of pages
if (self.maxPages <= 0) {
return;
}
// if we've got the max number of pages, remove the extra "new page" that is added in [super beginEditing]
if ([_pages count] >= self.maxPages ) {
[_pages removeLastObject];
[self updateContentSize:_pages.count]; // this has a compiler warning
// I added this method to NSObject via a category so I can pass primitives with performSelector
// [self performSelector:#selector(updateContentSize:) withInt:_pages.count waitUntilDone:NO];
}
}
I was wondering how to find out if a subview (in my case pageShadowView) has already been added to my view.
I've come up with this, but it doesn't really work:
if ([pageShadowView isKindOfClass:[self.view class]]) {
[self.view addSubview:pageShadowView];
}
Also, I'm still confused about the self.-thing. I know that this has to do with making clear that we are talking about the view of the current ViewController ... but do I really need it if there (1) are no other ViewControllers or (2) if it doesn't really matter because if I ever wanted to refer to another viewController, I'd make sure to call it?
I'm sorry if this is all very basic, but I'd be very grateful for your comments.
Here:
BOOL doesContain = [self.view.subviews containsObject:pageShadowView];
And yes, you need this self. There is no explicit ivar "view" on UIViewController. The self.view statement is actually a call on method [self view] which is a getter for UIViewController's view.
Give it a unique tag: view.tag = UNIQUE_TAG, then check the container view for existence:
BOOL alreadyAdded = [containerView viewWithTag:UNIQUE_TAG] != nil;
you can find a sub view like this
for(UIView *view in self.view.subviews)
{
if([view isKindOfClass:[UIView class]])
{
//here do your work
}
}
There's one more way to find, in Swift: isDescendant(of view: UIView) -> Bool or in Obj-C: - (BOOL)isDescendantOfView:(UIView *)view
Swift:
if myView.isDescendant(of: self.view) {
//myView is subview of self.view, remove it.
myView.removeFromSuperview()
} else {
//myView is not subview of self.view, add it.
self.view.addSubview(myView)
}
Obj-C:
if([myView isDescendantOfView:self.view]) {
//myView is subview of self.view, remove it.
[myView removeFromSuperView];
} else {
//myView is not subview of self.view, add it.
[self.view addSubView:myView];
}
SWIFT VERSION:
let doesContain = self.view?.subviews.contains(pageShadowView)
best and easy way to find that your view is exist or not , there are many way like you check a view is contain or not in super view or just view some time this method is failed because if the Uiview is already remove then error occur,
so code is here :
here errorView is my UiView
errorView.tag = 333
if ( self.view?.viewWithTag(333) != nil ){
print("contain")
}
else {
print("not contain")
}
To add to what coneybeare said, you could do the following. If you set your object.tag=100;
if ([self.view.superview viewWithTag:100] == nil){ //if statement executes if the object with tag 100 in view.superview is absent (nil)
if ([self.view viewWithTag:100] == nil){ //if statement executes if the object with tag 100 in view (not superview) is absent (nil)
add a retain value of the view
then check the retain value
if > 1 , then exist , if perfect should be 2
then release it once
I have noticed, in one of my views in an iPad app I am building the next button on the keyboard goes through all the UITextFields from left to right down the screen.
Is it possible somehow to make it go top to bottom then right, top to bottom?
So say I have to two long columns of text fields, I wan to go top to bottom not left to right, make sense?
Any help appreciated, thanks.
I don't think there is a way through IB, but you can do this way in code. You're not actually tabbing, you'd be using the return key.
Put this in your UITextField's delegate:
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {
BOOL shouldChangeText = YES;
if ([text isEqualToString:#"\n"]) {
// Find the next entry field
BOOL isLastField = YES;
for (UIView *view in [self entryFields]) {
if (view.tag == (textView.tag + 1)) {
[view becomeFirstResponder];
isLastField = NO;
break;
}
}
if (isLastField) {
[textView resignFirstResponder];
}
shouldChangeText = NO;
}
return shouldChangeText;
}
Found here: http://iphoneincubator.com/blog/tag/uitextfield
You'll want to implement UITextFieldDelegate's - (BOOL)textFieldShouldReturn:(UITextField *)textField method. An example of how to use this method to control the order is in this question.
I would like to elaborate on #sprocket's answer addressing the same issue. Just because something works out of the box doesn't mean you should stop thinking about a better way -- or even the right way -- of doing something. As he noticed the behavior is undocumented but fits our needs most of the time.
This wasn't enough for me though. Think of a RTL language and tabs would still tab left-to-right, not to mention the behavior is entirely different from simulator to device (device doesn't focus the first input upon tab). Most importantly though, Apple's undocumented implementation seems to only consider views currently installed in the view hierarchy.
Think of a form in form of (no pun intended) a table view. Each cell holds a single control, hence not all form elements may be visible at the same time. Apple would just cycle back up once you reached the bottommost (on screen!) control, instead of scrolling further down. This behavior is most definitely not what we desire.
So here's what I've come up with. Your form should be managed by a view controller, and view controllers are part of the responder chain. So you're perfectly free to implement the following methods:
#pragma mark - Key Commands
- (NSArray *)keyCommands
{
static NSArray *commands;
static dispatch_once_t once;
dispatch_once(&once, ^{
UIKeyCommand *const forward = [UIKeyCommand keyCommandWithInput:#"\t" modifierFlags:0 action:#selector(tabForward:)];
UIKeyCommand *const backward = [UIKeyCommand keyCommandWithInput:#"\t" modifierFlags:UIKeyModifierShift action:#selector(tabBackward:)];
commands = #[forward, backward];
});
return commands;
}
- (void)tabForward:(UIKeyCommand *)command
{
NSArray *const controls = self.controls;
UIResponder *firstResponder = nil;
for (UIResponder *const responder in controls) {
if (firstResponder != nil && responder.canBecomeFirstResponder) {
[responder becomeFirstResponder]; return;
}
else if (responder.isFirstResponder) {
firstResponder = responder;
}
}
[controls.firstObject becomeFirstResponder];
}
- (void)tabBackward:(UIKeyCommand *)command
{
NSArray *const controls = self.controls;
UIResponder *firstResponder = nil;
for (UIResponder *const responder in controls.reverseObjectEnumerator) {
if (firstResponder != nil && responder.canBecomeFirstResponder) {
[responder becomeFirstResponder]; return;
}
else if (responder.isFirstResponder) {
firstResponder = responder;
}
}
[controls.lastObject becomeFirstResponder];
}
Additional logic for scrolling offscreen responders visible beforehand may apply.
Another advantage of this approach is that you don't need to subclass all kinds of controls you may want to display (like UITextFields) but can instead manage the logic at controller level, where, let's be honest, is the right place to do so.