I have a RootViewController which creates a SecondViewController. Inside the SecondViewController in viewDidAppear, I create a UIScrollView and a UIPageControl and add them to the view. I also do this: scrollview.delegate = self. The SecondViewController is a <UIScrollViewDelegate>. I have also implemented scrollViewDidScroll inside the SecondViewController. All of this works, compiles and runs. However, when I touch the UIScrollView, the app crashes. For the life of me, I cannot figure out why. It is the stupidest problem, but I cannot solve it.
It is very similar to this problem: UIScrollView EXC_BAD_ACCESS crash in iOS
However, I tried those solutions and none of them work.
I have pasted some code below. I really appreciate the help.
RootViewController:
- (void)viewDidAppear:(BOOL)animated
{
SecondViewController *secondViewController = [[SecondViewController alloc] init];
secondViewController.view.frame = CGRectMake(50, 50, 925, 600);
secondViewController.view.backgroundColor = [UIColor lightGrayColor];
[self.view addSubview:secondViewController.view];
}
SecondViewController:
- (void)viewDidAppear:(BOOL)animated
{
CGRect scrollViewFrame = CGRectMake(50, 50, 824, 500);
self.scrollView = [[UIScrollView alloc] initWithFrame:scrollViewFrame];
self.scrollView.delegate = self;
self.scrollView.contentSize = CGSizeMake(self.scrollView.frame.size.width*3,
self.scrollView.frame.size.height);
self.scrollView.backgroundColor = [UIColor darkGrayColor];
self.scrollView.showsHorizontalScrollIndicator = YES;
self.scrollView.showsVerticalScrollIndicator = YES;
self.scrollView.pagingEnabled = YES;
[self.view addSubview:self.scrollView];
CGRect pageControlFrame = CGRectMake(0, 0, 50, 20);
self.pageControl = [[UIPageControl alloc] initWithFrame:pageControlFrame];
self.pageControl.numberOfPages = 3;
self.pageControl.currentPage = 0;
self.pageControl.backgroundColor = [UIColor grayColor];
[self.view addSubview:self.pageControl];
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
CGFloat pageWidth = self.scrollView.frame.size.width;
float fractionalPage = self.scrollView.contentOffset.x / pageWidth;
NSInteger page = lround(fractionalPage);
self.pageControl.currentPage = page;
}
your secondViewController object is deallocated as it is not retained anywhere only its view is retained as it is added as subview. You also need to retain secondViewController's object.
Related
I have a UIView called loadingView shows some UIActivityIndicatorView-like animation. There are two UIViewControllers that all have such UIView.
The initial UIViewController's code:
- (void)viewDidLoad {
self.loadingView = [[LoadingView alloc] initWithFrame:CGRectMake(10, 1, 120, 120)];
[self.view addSubview:self.loadingView];
}
Also it has a button to present the second UIViewController:
- (void)buttonPressed {
SecondViewController *sVC = [[SecondViewController alloc] init];
[self presentViewController:sVC animated:YES completion:nil];
}
The second ViewController's viewDidLoad method code:
- (void)viewDidLoad {
self.loadingView = [[LoadingView alloc] initWithFrame:CGRectMake(10, 1, 120, 120)];
[self.view addSubview:self.loadingView];
}
As you can see, the two UIViewControllers has the same viewDidLoad method code.
The loadingView works well in the initial UIViewController.
But in the second UIViewController, the loadingView only displays the black frame( I set the background colour to black).
Here is my loadingView implement code:
#define NUMBER_OF_DOT 15
#define DURATION 1.5
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
self.replicatorLayer = [[CAReplicatorLayer alloc] init];
self.replicatorLayer.frame = frame;
self.replicatorLayer.cornerRadius = 10.0;
self.replicatorLayer.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.86].CGColor;
self.replicatorLayer.position = self.center;
self.replicatorLayer.instanceDelay = DURATION/NUMBER_OF_DOT;
[self.layer addSublayer:self.replicatorLayer];
float size = frame.size.width*14/200;
self.dot = [[CALayer alloc] init];
self.dot.bounds = CGRectMake(0, 0, size, size);
self.dot.position = CGPointMake(frame.size.width/2, frame.size.height/5);
self.dot.backgroundColor = [UIColor colorWithWhite:0.8 alpha:1.0].CGColor;
self.dot.borderColor = [UIColor whiteColor].CGColor;
self.dot.borderWidth = 1.0;
self.dot.cornerRadius = 1.5;
self.dot.transform = CATransform3DMakeScale(0.01, 0.01, 0.01);
[self.replicatorLayer addSublayer:self.dot];
self.replicatorLayer.instanceCount = NUMBER_OF_DOT;
float angle = 2*M_PI/NUMBER_OF_DOT;
self.replicatorLayer.instanceTransform = CATransform3DMakeRotation(angle, 0.0, 0.0, 0.1);
self.shrink = [[CABasicAnimation alloc] init];
self.shrink.keyPath = #"transform.scale";
self.shrink.fromValue = [NSNumber numberWithFloat:1.0];
self.shrink.toValue = [NSNumber numberWithFloat:0.1];
self.shrink.duration = DURATION;
self.shrink.repeatCount = INFINITY;
[self.dot addAnimation:self.shrink forKey:nil];
}
return self;
}
-(void)viewDidAppear:(BOOL)animated
{
self.loadingView = [[LoadingView alloc] initWithFrame:CGRectMake(10, 1, 120, 120)];
[self.view addSubview:self.loadingView];
}
Put this code in viewDidAppear of SecondViewController so it works in present mode as well.
I have a UISegmentedControl where the first control will display the text within a UITextView while the second control displays a scrollable UIImageView.
In the initial startup, if I switch to the second control, the image displays and switching back to the first control, the image disappears and the UITextView shows.
However, when I switch to the second control the 2nd time and switch back to the first control, the image is still there and I cannot get the UITextView to show anymore.
My code has it to where the image is hidden and the text is shown in the first control, and vice versa in the second control.
Why was it working the first time, but then not working the second time I switched between controls?
What am I doing wrong?
Thanks
-(void)viewDidLoad
{
self.scrollView.delegate = self;
self.textView.text = #"THIS IS A TEST. THIS IS A TEST. THIS IS A TEST. THIS IS A TEST. THIS IS A TEST. THIS IS A TEST.";
self.textView.hidden = NO;
}
-(void)setScroller
{
CGSize scrollableSize = CGSizeMake(self.view.frame.size.width, self.view.frame.size.height);
[self.scrollView setContentSize:scrollableSize];
self.imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"test.png"] ];
self.imageView.frame = CGRectMake(0, 0, self.scrollView.frame.size.width, self.view.frame.size.height);
self.scrollView.backgroundColor = [UIColor blackColor];
self.scrollView.minimumZoomScale = 1.0 ;
self.scrollView.maximumZoomScale = self.imageView.image.size.width / self.scrollView.frame.size.width;
//self.scrollView.zoomScale = 1.0;
[self.scrollView addSubview:self.imageView];
}
-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.imageView;
}
- (IBAction)segmentedControl:(UISegmentedControl *)sender
{
if (self.segmentedControl.selectedSegmentIndex == 0)
{
// Display apppropriate info for About
self.imageView.hidden = YES;
self.textView.hidden = NO;
}
else
{
self.imageView.hidden = NO;
self.textView.hidden = YES;
[self setScroller];
}
}
You should remove [self setScroller]; from the - (IBAction)segmentedControl:(UISegmentedControl *)sender method, and put it in -(void)viewDidLoad instead. You're calling [self setScroller]; every time you switch to the second segment.
Your code should look like:
-(void)viewDidLoad
{
[super viewDidLoad];
self.scrollView.delegate = self;
[self setupScroller];
}
-(void)setupScroller
{
// Set contentSize
CGSize scrollableSize = CGSizeMake(self.view.frame.size.width, self.view.frame.size.height);
self.scrollView.contentSize = scrollableSize;
// Add textView
self.textView.text = #"THIS IS A TEST. THIS IS A TEST. THIS IS A TEST. THIS IS A TEST. THIS IS A TEST. THIS IS A TEST.";
self.textView.hidden = NO;
// Add ImageView
self.imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"test.png"]];
self.imageView.frame = CGRectMake(0, 0, self.scrollView.frame.size.width, self.view.frame.size.height);
self.imageView.hidden = YES;
[self.scrollView addSubview:self.imageView];
// Configure Zoom Scales and backgroundColor
self.scrollView.backgroundColor = [UIColor blackColor];
self.scrollView.minimumZoomScale = 1.0 ;
self.scrollView.maximumZoomScale = self.imageView.image.size.width / self.scrollView.frame.size.width;
}
-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.imageView;
}
- (IBAction)segmentedControl:(UISegmentedControl *)sender
{
if (self.segmentedControl.selectedSegmentIndex == 0)
{
// Display appropriate info for About
self.imageView.hidden = YES;
self.textView.hidden = NO;
}
else
{
self.imageView.hidden = NO;
self.textView.hidden = YES;
}
}
Your problem probably is that you creating a lot of instances of "imageView"
To solve your problem I suggest:
-(void)setScroller
{
CGSize scrollableSize = CGSizeMake(self.view.frame.size.width, self.view.frame.size.height);
[self.scrollView setContentSize:scrollableSize];
if(self.imageView == nil) {
self.imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"test.png"]];
[self.scrollView addSubview:self.imageView];
}
self.imageView.frame = CGRectMake(0, 0, self.scrollView.frame.size.width, self.view.frame.size.height);
self.scrollView.backgroundColor = [UIColor blackColor];
self.scrollView.minimumZoomScale = 1.0 ;
self.scrollView.maximumZoomScale = self.imageView.image.size.width / self.scrollView.frame.size.width;
//self.scrollView.zoomScale = 1.0;
[self.imageView setNeedsDisplay];
[self.imageView setImage:[UIImage imageNamed: #"test.png"]];
}
I've put only the Alloc of the self.imageView + the addSubView to the if,
All the rest are out side,
Now it will work
I'm trying to figure out an approach to build something like the image below, which is a list of items that when a section is clicked slides out content. It's a really common UX on most websites and what not. My idea is to have each gray box (button) slide out a UIView containing some other items. I'm still new to iOS development but I'm struggling to find how you can animate a UIView to slide down and push the content below it down as well. Hoping some one can give me a good starting point or point to some info outside the realm of the apple docs.
Thanks!
So if you just have a few views, I would not recommend the UITableView approach, since it is not so easy to customize with animations and table views usually want to fill the whole screen with cells. Instead write a expandable UIView subclass that has the desired two states. Add a method to switch between extended and collapsed state. On expanding/collapsing adjust their positions so that they always have enough space.
I provide you an example of views adjusting their frames. I guess it should be easy to do the same with auto layout constraints: give the views a fixed height constraint and change this on collapsing/expanding. The same way set the constraints between the views to be 0 so that they are stacked on top of each other.
Expandable View:
#interface ExpandingView(){
UIView *_expandedView;
UIView *_seperatorView;
BOOL _expanded;
}
#end
#implementation ExpandingView
- (id)init
{
self = [super initWithFrame:CGRectMake(15, 0, 290, 50)];
if (self) {
_expanded = NO;
self.clipsToBounds = YES;
_headerView = [[UIView alloc] initWithFrame:self.bounds];
_headerView.backgroundColor = [UIColor colorWithWhite:0.8 alpha:1];
[self addSubview:_headerView];
_seperatorView = [[UIView alloc] initWithFrame:CGRectMake(0, self.bounds.size.height-1, self.bounds.size.width, 1)];
_seperatorView.backgroundColor = [UIColor lightGrayColor];
[self addSubview:_seperatorView];
_expandedView = [[UIView alloc] initWithFrame:CGRectOffset(self.bounds, 0, self.bounds.size.height)];
_expandedView.backgroundColor = [UIColor blueColor];
[self addSubview:_expandedView];
}
return self;
}
- (void)layoutSubviews{
[self adjustLayout];
}
- (void)adjustLayout{
_headerView.frame = CGRectMake(0, 0, self.bounds.size.width, 50);
_seperatorView.frame = CGRectMake(0, 49, self.bounds.size.width, 1);
_expandedView.frame = CGRectMake(0, 50, self.bounds.size.width, self.bounds.size.height-50);
}
- (void)toggleExpandedState{
_expanded = !_expanded;
self.frame = CGRectMake(self.frame.origin.x, self.frame.origin.y, self.frame.size.width, _expanded?200:50);
[self adjustLayout];
}
#end
ViewController:
#interface ExpandingViewController (){
NSArray *_expandingViews;
}
#end
#implementation ExpandingViewController
- (void)viewDidLoad
{
[super viewDidLoad];
_expandingViews = #[
[[ExpandingView alloc] init],
[[ExpandingView alloc] init],
[[ExpandingView alloc] init],
];
for(ExpandingView *view in _expandingViews){
[view.headerView addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(expandingViewTapped:)]];
[self.view addSubview:view];
}
}
- (void)viewWillLayoutSubviews{
int y = 100;
for(ExpandingView *view in _expandingViews){
view.frame = CGRectOffset(view.bounds, (CGRectGetWidth(self.view.bounds)-CGRectGetWidth(view.bounds))/2, y);
y+=view.frame.size.height;
}
}
- (void)expandingViewTapped:(UITapGestureRecognizer*)tapper{
ExpandingView *view = (ExpandingView*)tapper.view.superview;
[UIView animateWithDuration:0.5 delay:0 usingSpringWithDamping:0.8 initialSpringVelocity:0 options:0 animations:^{
[view toggleExpandedState];
[self.view layoutIfNeeded];
} completion:nil];
}
after read some other cuestions about it i've tried:
on ViewController.m
DelegateScrollView ScrollView;
-(void)viewDidLoad
{
[super viewDidLoad];
ScrollView = [[DelegateScrollView alloc] initWithFrame:CGRectMake(0,- self.view.frame.size.height, self.view.frame.size.width, self.view.frame.size.height)];
ScrollView.delegate = ScrollView;
ScrollView.scrollEnabled = YES;
ScrollView.backgroundColor = [UIColor blackColor ];
ScrollView.maximumZoomScale = 5.0f;
ScrollView.minimumZoomScale = 1.0f;
[self.view addSubview:ScrollView];
[ScrollView setZoomScale:2 animated:YES];
}
DelegateScrollView.h:
#interface ChildDelegateScrollView : UIScrollView <UIScrollViewDelegate>
#end
and zoom never happends also i've tried this in ViewController.h: #interface ViewController : UIViewController <UIScrollViewDelegate> then set delegate like this ScrollView.delegate = self; and not work, how is the way to set correctly a delegate to a ScrollView?
This line from the UIScrollView class reference seems to be relevant:
For zooming and panning to work, the delegate must implement both viewForZoomingInScrollView: and scrollViewDidEndZooming:withView:atScale:
I was able to get a UILabel on a UIScrollView to zoom using this UIViewController code:
#import "ViewController.h"
#interface ViewController () <UIScrollViewDelegate> {
UIScrollView *_scrollView;
}
#end
#implementation ViewController
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0.0, 0.0, self.view.frame.size.width, self.view.frame.size.height)];
scrollView.delegate = self;
scrollView.scrollEnabled = YES;
scrollView.backgroundColor = [UIColor blackColor];
scrollView.maximumZoomScale = 5.0f;
scrollView.minimumZoomScale = 1.0f;
scrollView.contentSize = CGSizeMake(scrollView.frame.size.width, scrollView.frame.size.height);
[self.view addSubview:scrollView];
_scrollView = scrollView;
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(50.0, 50.0, 100.0, 25.0)];
label.backgroundColor = [UIColor grayColor];
label.textAlignment = NSTextAlignmentCenter;
label.text = #"Test";
[_scrollView addSubview:label];
}
- (void)viewDidAppear:(BOOL)animated
{
[_scrollView setZoomScale:4.0 animated:YES];
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return _scrollView.subviews.firstObject;
}
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale
{
}
#end
I am creating an iPAD app. I have got a MAIN VIEW controller which covers the whole screen. And I have another class DROP-DOWN Class which i will be using to mimic the functionality of a drop-down as in Windows OS components. For that I am using a simple button, a scroll view and a few labels. I instantiate an object of that class and use it in my MAIN VIEW controller. To create the effect of a drop down, I alter the instance's views frame on the touch up of the button in toggle mode.(Click once, frame increased, click again frame decreased).
The creation part was fine, and the function to toggle to worked fine when implemented on a single instance of the DROP DOWN object.
But the problem comes when I instantiate these objects thru a for loop. The views seem to just vanish on button click.
Here is the code within the dropdowns.
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor redColor];
UIScrollView *scrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(10,54,100,50)];
scrollView.contentSize = CGSizeMake(50, 100);
for (int i = 0; i< 10; i++)
{
UILabel *newLable = [[UILabel alloc]initWithFrame:CGRectMake(0, 10*i, 100, 10)];
[newLable setFont:[UIFont boldSystemFontOfSize:10]];
newLable.text = [NSString stringWithFormat:#"Testing %i",i];
[scrollView addSubview:newLable];
}
scrollView.backgroundColor = [UIColor greenColor];
[self.view addSubview:scrollView];
}
-(IBAction)btnClicked:(id)sender
{
if (!isOpen) {
oldRect = self.view.frame;
CGRect newFrame = self.view.frame;
newFrame.size = CGSizeMake(190, 200);
NSLog(#"New Frame - %f,%f,%f,%f",self.view.frame.origin.x,self.view.frame.origin.y,self.view.frame.size.height,self.view.frame.size.width);
self.view.frame = newFrame;
}
else {
self.view.frame = oldRect;
NSLog(#"Old Frame - %f,%f,%f,%f",self.view.frame.origin.x,self.view.frame.origin.y,self.view.frame.size.height,self.view.frame.size.width);
}
isOpen = !isOpen;
}
And here is how this is called from the main view.
- (void)viewDidLoad {
[super viewDidLoad];
[self performSelector:#selector(drawTheFilters)];
}
-(void)drawTheFilters
{
for (int i = 0; i<5 ; i++) {
DropDownView *dropView = [[DropDownView alloc]initWithNibName:#"DropDownView" bundle:[NSBundle mainBundle]];
CGRect newFrame = dropView.view.frame;
newFrame.origin = CGPointMake(200*i, 200);
dropView.view.frame = newFrame;
[self.view addSubview:dropView.view];
NSLog(#"Frame %i, %f,%f,%f,%f",i,dropView.view.frame.origin.x,dropView.view.frame.origin.y,dropView.view.frame.size.height,dropView.view.frame.size.width);
}
}