I have UIScrollView which has some views including UITextView. UITextView is bigger that the screen and has some text and has scrolling disabled. If the user tap on text view I would like to scroll my main scroll view to the position of the cursor in the text view. How can I do it? I tried use selectedRange but it doesn't seem to work.
Here is my a little more sofisticated solution:
- (void)scrollView:(UIScrollView *)scrollView scrollToTextInput:(UIResponder *)responder
{
if (!responder || ![responder conformsToProtocol:#protocol(UITextInput)] || ![responder isKindOfClass:[UIView class]]) {
return;
}
UIView<UITextInput> *textInput = (UIView<UITextInput> *)responder;
UIView *nextView = textInput;
while (nextView && (nextView != scrollView))
{
nextView = [nextView superview];
}
if (!nextView)
{
// Oh, this view is not from our `scrollView`.
return;
}
CGRect cursorRect = [textInput caretRectForPosition:textInput.selectedTextRange.start];
CGPoint cursorPoint = CGPointMake(CGRectGetMidX(cursorRect), CGRectGetMidY(cursorRect));
cursorPoint = [scrollView convertPoint:cursorPoint fromView:textInput];
CGFloat contentHeight = scrollView.contentSize.height;
CGFloat containerHeight = scrollView.frame.size.height;
CGFloat topInset = scrollView.contentInset.top;
CGFloat bottomInset = scrollView.contentInset.bottom;
CGFloat verticalInsets = scrollView.contentInset.top + scrollView.contentInset.bottom;
CGFloat offsetY = cursorPoint.y - (containerHeight - verticalInsets) / 2.f;
offsetY = MIN(MAX(offsetY, topInset), contentHeight - containerHeight + verticalInsets);
[scrollView setContentOffset:CGPointMake(scrollView.contentOffset.x, offsetY) animated:YES];
}
I did it in such way:
- (void)textViewDidBeginEditing:(UITextView *)textView
{
[self performSelector:#selector(scrollToCursorPosition:) withObject:textView afterDelay:0.05f];
}
- (void)scrollToCursorPosition:(UITextView *)textView
{
UITextRange *range = textView.selectedTextRange;
UITextPosition *position = range.start;
CGRect cursorRect = [textView caretRectForPosition:position];
CGPoint cursorPoint = CGPointMake(textView.frame.origin.x + cursorRect.origin.x, textView.frame.origin.y + cursorRect.origin.y);
[self setContentOffset:CGPointMake((cursorPoint.x - 10) * self.zoomScale, (cursorPoint.y - 10) * self.zoomScale) animated:NO];
}
if someone knows the better solution then please write the answer and I will accept it.
Related
I have a UIViewController and it's view hierarchy looks like this:
UIView
UIScrollView
UIImageView
I have code that positions the image view in the middle of the scroll view's frame, like so:
- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
[self recenterContent:scrollView];
}
- (void)recenterContent:(UIScrollView *)scrollView {
//this centers the content when it is smaller than the scrollView's bounds
CGFloat offsetX = MAX((scrollView.bounds.size.width - scrollView.contentSize.width) * 0.5, 0.0);
CGFloat offsetY = MAX((scrollView.bounds.size.height - scrollView.contentSize.height) * 0.5, 0.0);
self.scrollView.contentInset = UIEdgeInsetsMake(offsetY, offsetX, 0.f, 0.f);
}
This works fine when zooming the content, but when the view controller first loads it does not center. This is because the scrollView.contentSize is always 0. So my question is - when should I call this method after the scrollView.contentSize is set? When does that get set?
I have tried in viewDidLayoutSubviews, and the bounds of the scroll view is set then, but not the content size. Is there some method that I can use where the scroll view will be guaranteed to have the content size set?
Or is there a better way to keep the image centered when it is smaller than the scroll view? What I am trying to accomplish is to have it so the image view is not at the top of the scroll view and what I am using works, except when the scroll view's content size is not set. But if there is a better way of doing this without having to adjust the contentInset, I would be fine with that too.
Update
Here is what I have currently.
It is almost working, but no matter what I try, I cannot get it to look correct when the view loads. The way it works now is that it starts out off-center because when it calls the recenterContent method, before the view is displayed the content size of the scroll view is CGSizeZero, so the calculations are wrong. But if I try to recenter the content after the view has been displayed, then there is a visible delay before it gets centered.
I am just confused as to when the contentSize of the scroll view is set if I am using AutoLayout constraints to specify the size.
Here is my code. Can anyone see anything wrong with it?
#interface MyImageViewController ()
#property (strong, nonatomic) UIScrollView *scrollView;
#property (strong, nonatomic) UIImageView *imageView;
#property (assign, nonatomic) BOOL needsZoomScale;
#end
#implementation MyImageViewController
- (void)loadView {
self.view = [[UIView alloc] init];
[self.view addSubview:self.scrollView];
[self.scrollView addSubview:self.imageView];
self.needsZoomScale = YES;
[NSLayoutConstraint activateConstraints:#[
[self.scrollView.leadingAnchor constraintEqualToAnchor:self.view.leadingAnchor],
[self.scrollView.topAnchor constraintEqualToAnchor:self.view.topAnchor],
[self.scrollView.trailingAnchor constraintEqualToAnchor:self.view.trailingAnchor],
[self.scrollView.bottomAnchor constraintEqualToAnchor:self.view.bottomAnchor],
[self.imageView.leadingAnchor constraintEqualToAnchor:self.scrollView.contentLayoutGuide.leadingAnchor],
[self.imageView.topAnchor constraintEqualToAnchor:self.scrollView.contentLayoutGuide.topAnchor],
[self.imageView.trailingAnchor constraintEqualToAnchor:self.scrollView.contentLayoutGuide.trailingAnchor],
[self.imageView.bottomAnchor constraintEqualToAnchor:self.scrollView.contentLayoutGuide.bottomAnchor]
]];
}
- (void)viewDidLoad {
[super viewDidLoad];
UITapGestureRecognizer *doubleTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(doubleTapZoom:)];
doubleTapGesture.numberOfTapsRequired = 2;
[self.imageView addGestureRecognizer:doubleTapGesture];
}
- (CGRect)zoomRectForScrollView:(UIScrollView *)scrollView withScale:(CGFloat)scale withCenter:(CGPoint)center {
CGRect zoomRect;
//the zoom rect is in the content view's coordinates. At a zoom scale of 1.0, the zoom rect would be the size
//of the scroll view's bounds. As the zoom scale decreases, so more content is visible, the size of the rect
//grows.
zoomRect.size.width = scrollView.frame.size.width / scale;
zoomRect.size.height = scrollView.frame.size.height / scale;
//choose an origin so as to get the right center
zoomRect.origin.x = center.x - (zoomRect.size.width / 2.0);
zoomRect.origin.y = center.y - (zoomRect.size.height / 2.0);
return zoomRect;
}
- (void)doubleTapZoom:(UITapGestureRecognizer *)sender {
UIView *tappedView = sender.view;
CGPoint tappedPoint = [sender locationInView:tappedView];
if (tappedPoint.x <= 0) {
tappedPoint.x = 1;
}
if (tappedPoint.y <= 0) {
tappedPoint.y = 1;
}
if (tappedPoint.x >= tappedView.bounds.size.width) {
tappedPoint.x = tappedView.bounds.size.width - 1;
}
if (tappedPoint.y >= tappedView.bounds.size.height) {
tappedPoint.y = tappedView.bounds.size.height - 1;
}
CGFloat zoomScale;
if (self.scrollView.zoomScale < 1) {
zoomScale = 1;
} else if (self.scrollView.zoomScale < self.scrollView.maximumZoomScale) {
zoomScale = self.scrollView.maximumZoomScale;
} else {
zoomScale = self.scrollView.minimumZoomScale;
}
CGRect zoomRect = [self zoomRectForScrollView:self.scrollView withScale:zoomScale withCenter:tappedPoint];
[self.scrollView zoomToRect:zoomRect animated:YES];
}
- (UIScrollView *)scrollView {
if (!self->_scrollView) {
self->_scrollView = [[UIScrollView alloc] init];
self->_scrollView.translatesAutoresizingMaskIntoConstraints = NO;
self->_scrollView.minimumZoomScale = 0.1f;
self->_scrollView.maximumZoomScale = 4.0f;
self->_scrollView.bounces = YES;
self->_scrollView.bouncesZoom = YES;
self->_scrollView.delegate = self;
self->_scrollView.backgroundColor = [UIColor blackColor];
}
return self->_scrollView;
}
- (UIImageView *)imageView {
if (!self->_imageView) {
self->_imageView = [[UIImageView alloc] init];
self->_imageView.translatesAutoresizingMaskIntoConstraints = NO;
self->_imageView.userInteractionEnabled = YES;
}
return self->_imageView;
}
- (UIImage *)image {
return self.imageView.image;
}
- (void)setImage:(UIImage *)image {
self.imageView.image = image;
self.needsZoomScale = YES;
[self updateZoomScale];
}
- (void)updateZoomScale {
if (self.needsZoomScale && self.image) {
CGSize size = self.view.bounds.size;
if (size.width == 0.0f || size.height == 0.0f) {
return;
}
UIImage *image = self.image;
CGSize imageSize = CGSizeMake(image.size.width * image.scale, image.size.height * image.scale);
if (imageSize.width > 0 && imageSize.height > 0) {
CGFloat widthScale = size.width / imageSize.width;
CGFloat heightScale = size.height / imageSize.height;
CGFloat minScale = MIN(widthScale, heightScale);
self.scrollView.minimumZoomScale = minScale;
self.scrollView.zoomScale = minScale;
self.needsZoomScale = NO;
}
}
}
- (void)viewWillLayoutSubviews {
[super viewWillLayoutSubviews];
[self updateZoomScale];
}
- (void)viewDidLayoutSubviews {
[super viewDidLayoutSubviews];
[self recenterContent:self.scrollView];
}
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
[self recenterContent:self.scrollView];
}
#pragma mark - UIScrollViewDelegate
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
return self.imageView;
}
- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
[self recenterContent:scrollView];
}
- (void)recenterContent:(UIScrollView *)scrollView {
//this centers the content when it is smaller than the scrollView's bounds
CGFloat offsetX = MAX((scrollView.bounds.size.width - scrollView.contentSize.width) * 0.5, 0.0);
CGFloat offsetY = MAX((scrollView.bounds.size.height - scrollView.contentSize.height) * 0.5, 0.0);
self.scrollView.contentInset = UIEdgeInsetsMake(offsetY, offsetX, 0.f, 0.f);
}
#end
The problem is that a UIImageView has an intrinsic content size of 0,0 -- so your code is initially putting the a 0x0 image view at the center of the scroll view.
I've made a few changes to the code you posted... see comments (I "wrapped" the changes in
// ---------------------------------
comment lines:
#interface MyImageViewController : UIViewController <UIScrollViewDelegate>
#end
#interface MyImageViewController ()
#property (strong, nonatomic) UIScrollView *scrollView;
#property (strong, nonatomic) UIImageView *imageView;
#property (assign, nonatomic) BOOL needsZoomScale;
#end
#implementation MyImageViewController
- (void)loadView {
self.view = [[UIView alloc] init];
[self.view addSubview:self.scrollView];
[self.scrollView addSubview:self.imageView];
self.needsZoomScale = YES;
// ---------------------------------
// respect safe area
UILayoutGuide *g = [self.view safeAreaLayoutGuide];
// saves on a little typing
UILayoutGuide *sg = [self.scrollView contentLayoutGuide];
// ---------------------------------
[NSLayoutConstraint activateConstraints:#[
[self.scrollView.leadingAnchor constraintEqualToAnchor:g.leadingAnchor],
[self.scrollView.topAnchor constraintEqualToAnchor:g.topAnchor],
[self.scrollView.trailingAnchor constraintEqualToAnchor:g.trailingAnchor],
[self.scrollView.bottomAnchor constraintEqualToAnchor:g.bottomAnchor],
[self.imageView.leadingAnchor constraintEqualToAnchor:sg.leadingAnchor],
[self.imageView.topAnchor constraintEqualToAnchor:sg.topAnchor],
[self.imageView.trailingAnchor constraintEqualToAnchor:sg.trailingAnchor],
[self.imageView.bottomAnchor constraintEqualToAnchor:sg.bottomAnchor]
]];
}
- (void)viewDidLoad {
[super viewDidLoad];
UITapGestureRecognizer *doubleTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(doubleTapZoom:)];
doubleTapGesture.numberOfTapsRequired = 2;
[self.imageView addGestureRecognizer:doubleTapGesture];
}
- (CGRect)zoomRectForScrollView:(UIScrollView *)scrollView withScale:(CGFloat)scale withCenter:(CGPoint)center {
CGRect zoomRect;
//the zoom rect is in the content view's coordinates. At a zoom scale of 1.0, the zoom rect would be the size
//of the scroll view's bounds. As the zoom scale decreases, so more content is visible, the size of the rect
//grows.
zoomRect.size.width = scrollView.frame.size.width / scale;
zoomRect.size.height = scrollView.frame.size.height / scale;
//choose an origin so as to get the right center
zoomRect.origin.x = center.x - (zoomRect.size.width / 2.0);
zoomRect.origin.y = center.y - (zoomRect.size.height / 2.0);
return zoomRect;
}
- (void)doubleTapZoom:(UITapGestureRecognizer *)sender {
UIView *tappedView = sender.view;
CGPoint tappedPoint = [sender locationInView:tappedView];
if (tappedPoint.x <= 0) {
tappedPoint.x = 1;
}
if (tappedPoint.y <= 0) {
tappedPoint.y = 1;
}
if (tappedPoint.x >= tappedView.bounds.size.width) {
tappedPoint.x = tappedView.bounds.size.width - 1;
}
if (tappedPoint.y >= tappedView.bounds.size.height) {
tappedPoint.y = tappedView.bounds.size.height - 1;
}
CGFloat zoomScale;
if (self.scrollView.zoomScale < 1) {
zoomScale = 1;
} else if (self.scrollView.zoomScale < self.scrollView.maximumZoomScale) {
zoomScale = self.scrollView.maximumZoomScale;
} else {
zoomScale = self.scrollView.minimumZoomScale;
}
CGRect zoomRect = [self zoomRectForScrollView:self.scrollView withScale:zoomScale withCenter:tappedPoint];
[self.scrollView zoomToRect:zoomRect animated:YES];
}
- (UIScrollView *)scrollView {
if (!self->_scrollView) {
self->_scrollView = [[UIScrollView alloc] init];
self->_scrollView.translatesAutoresizingMaskIntoConstraints = NO;
self->_scrollView.minimumZoomScale = 0.1f;
self->_scrollView.maximumZoomScale = 4.0f;
self->_scrollView.bounces = YES;
self->_scrollView.bouncesZoom = YES;
self->_scrollView.delegate = self;
self->_scrollView.backgroundColor = [UIColor blackColor];
}
return self->_scrollView;
}
- (UIImageView *)imageView {
if (!self->_imageView) {
self->_imageView = [[UIImageView alloc] init];
self->_imageView.translatesAutoresizingMaskIntoConstraints = NO;
self->_imageView.userInteractionEnabled = YES;
}
return self->_imageView;
}
- (UIImage *)image {
return self.imageView.image;
}
- (void)setImage:(UIImage *)image {
self.imageView.image = image;
// ---------------------------------
// set the frame here
self.imageView.frame = CGRectMake(0.0, 0.0, image.size.width, image.size.height);
// ---------------------------------
// not needed ... unless maybe changing the image while view is showing?
//self.needsZoomScale = YES;
//[self updateZoomScale];
}
- (void)updateZoomScale {
if (self.needsZoomScale && self.image) {
CGSize size = self.view.bounds.size;
if (size.width == 0.0f || size.height == 0.0f) {
return;
}
UIImage *image = self.image;
CGSize imageSize = CGSizeMake(image.size.width * image.scale, image.size.height * image.scale);
if (imageSize.width > 0 && imageSize.height > 0) {
CGFloat widthScale = size.width / imageSize.width;
CGFloat heightScale = size.height / imageSize.height;
CGFloat minScale = MIN(widthScale, heightScale);
self.scrollView.minimumZoomScale = minScale;
self.scrollView.zoomScale = minScale;
self.needsZoomScale = NO;
}
}
}
// ---------------------------------
// Don't need this
//- (void)viewWillLayoutSubviews {
// [super viewWillLayoutSubviews];
// [self updateZoomScale];
//}
// ---------------------------------
- (void)viewDidLayoutSubviews {
[super viewDidLayoutSubviews];
// ---------------------------------
// update zoom scale here
[self updateZoomScale];
// ---------------------------------
[self recenterContent:self.scrollView];
}
// ---------------------------------
// Don't need this
//- (void)viewDidAppear:(BOOL)animated {
// [super viewDidAppear:animated];
// [self recenterContent:self.scrollView];
//}
// ---------------------------------
#pragma mark - UIScrollViewDelegate
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
return self.imageView;
}
- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
[self recenterContent:scrollView];
}
- (void)recenterContent:(UIScrollView *)scrollView {
//this centers the content when it is smaller than the scrollView's bounds
CGFloat offsetX = MAX((scrollView.bounds.size.width - scrollView.contentSize.width) * 0.5, 0.0);
CGFloat offsetY = MAX((scrollView.bounds.size.height - scrollView.contentSize.height) * 0.5, 0.0);
self.scrollView.contentInset = UIEdgeInsetsMake(offsetY, offsetX, 0.f, 0.f);
}
#end
and here's how I call it:
MyImageViewController *vc = [MyImageViewController new];
UIImage *img = [UIImage imageNamed:#"bkg"];
if (nil == img) {
NSLog(#"Could not load image!!!!");
return;
}
[vc setImage:img];
[self.navigationController pushViewController:vc animated:YES];
I am replicating Facebook/Apple News hide/show nav bar functionality. I can hide/show the nav bar but I don't know how to calculate the scroll view's content inset as the nav bar frame.origin.y changes. I want the scroll view content inset to follow nav bar's position so that it all looks smooth.
Here's what I'm doing:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
CGFloat navBarTopLength = self.navigationController.topLayoutGuide.length; // 20
CGRect frame = self.navigationController.navigationBar.frame;
CGFloat size = frame.size.height - (navBarTopLength + 1);
CGFloat framePercentageHidden = ((navBarTopLength - frame.origin.y) / (frame.size.height - 1));
CGFloat scrollOffset = scrollView.contentOffset.y;
CGFloat scrollDiff = scrollOffset - self.previousScrollViewYOffset;
CGFloat scrollHeight = scrollView.frame.size.height;
CGFloat scrollContentSizeHeight = scrollView.contentSize.height + scrollView.contentInset.bottom;
if (scrollOffset <= -scrollView.contentInset.top) {
frame.origin.y = navBarTopLength; // showing nav bar
} else if ((scrollOffset + scrollHeight) >= scrollContentSizeHeight) {
frame.origin.y = -size;
} else {
frame.origin.y = MIN(navBarTopLength, MAX(-size, frame.origin.y - scrollDiff));
}
CGFloat top;
if (self.previousScrollViewYOffset > scrollOffset) {
NSLog(#"scrolling down"); //scrolling down
top = self.navigationController.navigationBar.frame.size.height + frame.origin.y;
} else {
NSLog(#"scrolling up"); //scrolling up
top = (navBarTopLength + 1) + frame.origin.y;
}
[self.navigationController.navigationBar setFrame:frame];
[self updateBarButtonItems:(1 - framePercentageHidden)];
scrollView.contentInset = UIEdgeInsetsMake(top, 0, 0, 0);
self.previousScrollViewYOffset = scrollOffset;
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
[self stoppedScrolling];
}
- (void)updateBarButtonItems:(CGFloat)alpha {
[self.navigationItem.leftBarButtonItems enumerateObjectsUsingBlock:^(UIBarButtonItem *item, NSUInteger i, BOOL *stop) {
item.customView.alpha = alpha;
}];
[self.navigationItem.rightBarButtonItems enumerateObjectsUsingBlock:^(UIBarButtonItem *item, NSUInteger i, BOOL *stop) {
item.customView.alpha = alpha;
}];
self.navigationItem.titleView.alpha = alpha;
self.navigationController.navigationBar.tintColor =[self.navigationController.navigationBar.tintColor colorWithAlphaComponent:alpha];
}
- (void)animateNavBarTo:(CGFloat)y {
[UIView animateWithDuration:0.2
animations:^{
CGRect frame = self.navigationController.navigationBar.frame;
BOOL hide = frame.origin.y >= y;
CGFloat alpha = (hide ? 0 : 1);
frame.origin.y = y;
[self.navigationController.navigationBar setFrame:frame];
[self updateBarButtonItems:alpha];
self.navBarHidden = hide;
}];
}
- (void)stoppedScrolling {
CGRect frame = self.navigationController.navigationBar.frame;
if (frame.origin.y < 20) {
[self animateNavBarTo:-(frame.size.height - 21)];
}
}
I know that I should be changing the content inset in scrollViewDidScroll as I'm calculating a new frame for the nav bar. The way I'm currently calculating new top inset makes the whole UI shake and everything breaks shortly after with BAD ACCESS
I am adding a UIView to the end of my UIScrollView as follows -
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
float scrollViewHeight = scrollView.frame.size.height;
float scrollContentSizeHeight = scrollView.contentSize.height;
float scrollOffset = scrollView.contentOffset.y;
if (scrollOffset == 0)
{
}
else if (scrollOffset + scrollViewHeight >= scrollContentSizeHeight)
{
UIView *paintView=[[UIView alloc]initWithFrame:CGRectMake(0, scrollOffset + scrollViewHeight + 20, self.view.frame.size.width, 200)];
[paintView setBackgroundColor:[UIColor yellowColor]];
[self.containerScrollView addSubview:paintView];
}
}
This added the view at the end, but I am not able to scroll that view. How do I enable scrolling to the newly added view as well?
You can set scrollview's contentInset
scrollView.contentInset = UIEdgeInsetsMake(0,0,extensionHeight,0);
but you probably don't wanna add subview in - (void)scrollViewDidScroll:(UIScrollView *)scrollView ,because this function would be invoked many times, your subview would be created many times.
If you have to add subview in it, I suggest you create a property paintView, and check if it is nil, if it is, create it, if not, just don't do anything
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
float scrollViewHeight = scrollView.frame.size.height;
float scrollContentSizeHeight = scrollView.contentSize.height;
float scrollOffset = scrollView.contentOffset.y;
if (scrollOffset == 0)
{
}
else if (scrollOffset + scrollViewHeight >= scrollContentSizeHeight)
{
scrollView.contentInset = UIEdgeInsetsMake(0,0,extensionHeight,0);
if (!_paintView) {
_paintView=[[UIView alloc]initWithFrame:CGRectMake(0, scrollOffset + scrollViewHeight + 20, self.view.frame.size.width, 200)];
[_paintView setBackgroundColor:[UIColor yellowColor]];
[self.containerScrollView addSubview:_paintView];
}
}
}
I did my Top View and Bottom View (UIViews) hide while the UITableView is scrolling. Now, I need to check if the user begin drag the UITableview to up again and back the uiviews for the initial position. I have the following code to do the first step: hidden/show while scrolling uitableview
-(void)scrollViewDidScroll:(UIScrollView *)scrollView {
if(!self.isScrollingFast) {
CGRect screenBound = [[UIScreen mainScreen] bounds];
CGSize screenSize = screenBound.size;
CGFloat screenWidth = screenSize.width;
CGFloat screenHeight = screenSize.height;
NSInteger yOffset = scrollView.contentOffset.y;
if (yOffset > 0) {
self.tabBar.frame = CGRectMake(self.tabBar.frame.origin.x, self.originalFrame.origin.y + yOffset, self.tabBar.frame.size.width, self.tabBar.frame.size.height);
self.viewTopo.frame = CGRectMake(self.viewTopo.frame.origin.x, self.originalFrameTopo.origin.y - yOffset, self.viewTopo.frame.size.width, self.viewTopo.frame.size.height);
if(self.originalFrameHidingView.origin.y - yOffset >= 0) {
self.hidingView.frame = CGRectMake(self.hidingView.frame.origin.x, self.originalFrameHidingView.origin.y - yOffset, self.hidingView.frame.size.width, self.hidingView.frame.size.height);
}
else {
self.hidingView.frame = CGRectMake(self.hidingView.frame.origin.x, -10, self.hidingView.frame.size.width, self.hidingView.frame.size.height);
}
[self.tbPertos setFrame:CGRectMake(self.tbPertos.frame.origin.x, self.hidingView.frame.origin.y + self.hidingView.frame.size.height, self.tbPertos.frame.size.width, self.tbPertos.frame.size.height)];
if(self.tbPertos.frame.size.height + self.tbPertos.frame.origin.y + yOffset <= screenHeight)
self.tbPertos.frame = CGRectMake(self.tbPertos.frame.origin.x, self.tbPertos.frame.origin.y, self.tbPertos.frame.size.width, self.tbPertos.frame.size
.height+yOffset);
else {
self.tbPertos.frame = CGRectMake(self.tbPertos.frame.origin.x, self.tbPertos.frame.origin.y, self.tbPertos.frame.size.width, screenHeight - self.tbPertos.frame.origin.y);
}
}
if (yOffset < 1) {
self.tabBar.frame = self.originalFrame;
self.viewTopo.frame = self.originalFrameTopo;
self.hidingView.frame = self.originalFrameHidingView;
self.tbPertos.frame = CGRectMake(self.tbPertos.frame.origin.x, self.hidingView.frame.origin.y + self.hidingView.frame.size.height, self.tbPertos.frame.size.width, screenHeight - self.tbPertos.frame.origin.y);
}
}
}
And there's the code which I'm trying to do the Top and Bottom View reappear when the user begin scroll up. Independently wheres the scroll offset.
-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
CGPoint currentOffset = scrollView.contentOffset;
NSTimeInterval currentTime = [NSDate timeIntervalSinceReferenceDate];
NSTimeInterval timeDiff = currentTime - self.lastOffsetCapture;
CGFloat distance = currentOffset.y - self.lastOffset.y;
//The multiply by 10, / 1000 isn't really necessary.......
if (distance < 0) {
if(!self.isScrollingFast) {
NSLog(#"voltar posicao normal");
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:0.5];
[UIView setAnimationDelay:1.0];
[UIView setAnimationCurve:UIViewAnimationCurveEaseOut];
self.tabBar.frame = self.originalFrame;
self.viewTopo.frame = self.originalFrameTopo;
self.hidingView.frame = self.originalFrameHidingView;
self.tbPertos.frame = self.originalFrameTbPertos;
self.isScrollingFast = YES;
[UIView commitAnimations];
}
} else {
self.isScrollingFast = NO;
}
self.lastOffset = currentOffset;
self.lastOffsetCapture = currentTime;
}
Here i implemented code for UIView Hide / Show when tableview scrolling. When tableview scrolling down then UIView is hidden and when scrolling up then UIView show. I hope it's working for you...!
Step 1:- Make one property in .h file
#property (nonatomic) CGFloat previousContentOffset;
Step 2:- Write down this code in scrollViewDidScroll Method.
-(void)scrollViewDidScroll:(UIScrollView *)scrollView {
CGFloat currentContentOffset = scrollView.contentOffset.y;
if (currentContentOffset > self.previousContentOffset) {
// scrolling towards the bottom
[self.subButtonView setHidden:YES];
} else if (currentContentOffset < self.previousContentOffset) {
// scrolling towards the top
[self.subButtonView setHidden:NO];
}
self.previousContentOffset = currentContentOffset;
}
My problem is i am not able to get the exact CGRect value after zooming for zooming in UIScrollview i am using zoomToRect method of UIScrollview. while zooming i am setting the contentOffset property.
Code follows:
if(image != nil) {
CGSize zoomViewSize = image.frame.size;
CGSize scrollViewSize = self.bounds.size;
if(zoomViewSize.width < scrollViewSize.width) {
anOffset.x = -(scrollViewSize.width - zoomViewSize.width) / 2.0;
}
if(zoomViewSize.height < scrollViewSize.height) {
anOffset.y = -(scrollViewSize.height - zoomViewSize.height) / 2.0;
}
}
super.contentOffset = anOffset;
after zooming i am setting the content inset property so that image comes in the center. for content inset the code is given below.
-(void)zoomtorect:(CGRect)rect animated:(BOOL)animated {
[super zoomtorect:rect animated:YES];
CGFloat pageWidth = image.image.size.height;
CGSize imageSize = rect.size;
CGSize zoomedImageSize = CGSizeMake(imageSize.width * 0.2, imageSize.height * 0.2);
CGSize pageSize = self.bounds.size;
//scLayer.frame = rect;
UIEdgeInsets inset = UIEdgeInsetsZero;
if (pageSize.width > zoomedImageSize.width) {
inset.left = (pageSize.width - zoomedImageSize.width) / 2;
inset.right = inset.left;
}
if (pageSize.height > zoomedImageSize.height) {
inset.top = (pageSize.height - zoomedImageSize.height) / 2;
inset.bottom = inset.top;
}
self.contentInset = inset;
}
this code shifts my image view between screen. Every thing works fine here. My problem is i have to show only zoom portion of the imageView rest will be black. For calculating the zoomed area i am doing the following calculation.
CGSize imageSize = rect.size;
CGSize zoomedImageSize = CGSizeMake(imageSize.width * scroll.maximumZoomScale, imageSize.height *scroll.maximumZoomScale);
CGSize pageSize = scroll.bounds.size;
UIEdgeInsets inset = UIEdgeInsetsZero;
if (pageSize.width > zoomedImageSize.width) {
inset.left = (pageSize.width - zoomedImageSize.width) / 2;
inset.right = inset.left;
}
if (pageSize.height > zoomedImageSize.height) {
inset.top = (pageSize.height - zoomedImageSize.height) / 2;
inset.bottom = inset.top;
}
CGRect zoomRect = [scroll convertRect:rect fromView:image];
CGRect zoomRect1 = CGRectMake(inset.left, inset.top+50, zoomRect.size.width, zoomRect.size.height);
this zoomRect1 is the zoomed area of the image this value is not exact what i am seeing in the screen. some where i am doing calculation mistake please help me out. But i am not getting the exact value of the zoomed image area.
Thanks in advance
Use this.. Works Perfectly
- (void)handleDoubleTap:(UIGestureRecognizer *)recognizer
{
if(isAlreadyZoomed)
{
CGPoint Pointview = [recognizer locationInView:recognizer.view];
CGFloat newZoomscal = 3.0;
CGSize scrollViewSize = self.scrollContainer.bounds.size;
CGFloat width = scrollViewSize.width/newZoomscal;
CGFloat height = scrollViewSize.height /newZoomscal;
CGFloat xPos = Pointview.x-(width/2.0);
CGFloat yPos = Pointview.y-(height/2.0);
CGRect rectTozoom=CGRectMake(xPos, yPos, width, height);
[self.scrollContainer zoomToRect:rectTozoom animated:YES];
[self.scrollContainer setZoomScale:3.0 animated:YES];
isAlreadyZoomed = NO;
}
else
{
[self.scrollContainer setZoomScale:1.0 animated:YES];
isAlreadyZoomed = YES;
}
}
isAlreadyZoomed is a BOOL value