i am trying to remake (mostly) the same sample example provided by apple which is called tapToZoom.
the difference is that i am using storyboard instead of a classic nib file as the example shows, i set an image inside the scrollView.
the problem is that the zoom don't work e.g. here:
//set the initial zoom scale
float minimumScale = [myScroll frame].size.width / [myImage frame].size.width;
NSLog(#"%f",minimumScale);
[myScroll setMinimumZoomScale:minimumScale];
[myScroll setZoomScale:minimumScale];
NSLog()#"%f",[myScroll zoomScale];
the logs return 0.6 for the first one and 1.0 for the second which is supposed to be 0.6.
anyone got this problem before?
[EDIT]: the previous lines are into my viewDidLoad method.
I think you should implement
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView;
Try this delegate method.
Related
I'd like to implement a "zoom" effect on a paging UIScrollView that I've created, but I am having a lot of difficulty. My goal is that as a user begins to scroll to the next page, the current page zooms out to become a little bit smaller. As the next page comes into view, it zooms in until it becomes its full size. The closest thing I could find to an example was this...
https://www.pinterest.com/pin/147141112804210631/
Can anyone give me some pointers on how to accomplish this? I've been banging my head against a wall for the last 3 days on this.
I would recommend using the scrollView.contentOffset.y of your paginated UIScrollView to keep track of the scroll and to use that value to animate the transform of your views inside the UIScrollView.
So add your paginated scrollview and make self as delegate.
paginatedScrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, [[self view] bounds].size.width, [[self view] bounds].size.height-paginatedScrollViewYOffset)];
[self.view addSubview:paginatedScrollView];
paginatedScrollView.pagingEnabled = YES;
[paginatedScrollView setShowsVerticalScrollIndicator:NO];
[paginatedScrollView setShowsHorizontalScrollIndicator:NO];
[paginatedScrollView setAlwaysBounceHorizontal:NO];
[paginatedScrollView setAlwaysBounceVertical:YES];
paginatedScrollView.backgroundColor = [UIColor clearColor];
paginatedScrollView.contentSize = CGSizeMake([[self view] bounds].size.width, [[self view] bounds].size.height*2); //this must be the appropriate size depending of the number of pages you want to scroll
paginatedScrollView.delegate = self;
Then use the delegate method scrollViewDidScroll to keep track of the scrollView.contentOffset.y
- (void) scrollViewDidScroll:(UIScrollView *)scrollView {
NSLog(#"Scroll Content Offset Y: %f",scrollView.contentOffset.y);
//use here scrollView.contentOffset.y as multiplier with view.transform = CGAffineTransformMakeScale(0,0) or with view.frame to animate the zoom effect
}
Use this Code scrollview its zoom in when scroll next page, the code is given below,
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
GridCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"CollectCell" forIndexPath:indexPath];
cell.myscrollview.minimumZoomScale = 5.0;
cell.myscrollview.zoomScale = 5.0;
cell.myscrollview.contentSize = cell.contentView.bounds.size;
return cell;
}
if you change the zoom scale value its automatically zoom in or zoom out to be showed when scroll next or previous page.
hope its helpful.
I actually just posted an answer to a very similar question, where somebody tried to achieve this effect using a UICollectionView. The link to my answer is here: https://stackoverflow.com/a/36710965/3723434
Relevant piece of code I will post here:
So another approach would be to to set a CGAffineTransformMakeScale( , ) in the UIScrollViewDidScroll where you dynamically update the pages' size based on their distance from the center of the screen.
For every page, calculate the distance of its center to the center of yourScrollView
The center of yourScrollView can be found using this nifty method: CGPoint point = [self.view convertPoint:yourScrollView.center toView:*yourScrollView];
Now set up a rule, that if the page's center is further than x away, the size of the page is for example the 'normal size', call it 1. and the closer it gets to the center, the closer it gets to twice the normal size, 2.
then you can use the following if/else idea:
if (distance > x) {
page.transform = CGAffineTransformMakeScale(1.0f, 1.0f);
} else if (distance <= x) {
float scale = MIN(distance/x) * 2.0f;
page.transform = CGAffineTransformMakeScale(scale, scale);
}
What happens is that the page's size will exactly follow your touch. Let me know if you have any more questions as I'm writing most of this out of the top of my head).
I've done some work on stylized app guide page before.
For Me, I would use CADisplayLink to track the contentOffset.x of the scrollView, associate the value with your animation process. Don't put your views on the scrollView, put them on an overlay view of this scrollView.
This solution follows the philosophy: Fake it before you make it.
Based on CADisplayLink and physics simulation of UIScrollView, you will get smooth animation. Believe me.
What you really want isn't a UIScrollView, it's a UICollectionView with a custom layout. UICollectionViewLayoutAttributes has a transform property that you can set.
Say for example, in layoutAttributesForElementsInRect::
override func layoutAttributesForElementsInRect(rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
guard let attributes = super.layoutAttributesForElementsInRect(rect) else {
return nil
}
return attributes.map { attribute -> UICollectionViewLayoutAttributes in
if attribute.frame.origin.y < 0 {
let scale = -attribute.frame.origin.y / attribute.frame.height
attribute.transform = CGAffineTransformMakeScale(scale, scale)
}
return attribute
}
}
Here, you're filtering by if the element is on the screen (so non-visible elements won't be counted) and checking to see if the y offset is less than 0. If it is, you take the difference between the negated y value and the item's height and turn that into a proportional scale.
You can do it however you want, if you want the scale to be between 1 and 0.5 for example. I like this way of doing things over mucking around with a scroll view.
I've a UIScrollView with other subviews inside an UIImageWiew and I need to rotate the whole content, so I take this road:
imageView.transform = CGAffineTransformMakeRotation([self.orientation floatValue]);
Good, works perfectly.
Being the ImageView inside a scroll view, I also need to set zoomScale in order to resize image inside, and I do it in this way:
- (void)updateZoom {
const float minZoom = MIN(self.view.bounds.size.width / self.imageView.image.size.width,
self.view.bounds.size.height / self.imageView.image.size.height);
if (minZoom > 1) {
return;
}
self.scrollView.minimumZoomScale = minZoom;
self.scrollView.zoomScale = minZoom;
}
updateZoom has the effect to "reset" initial transformation, so image come back to original orientation.
Generally, each time I modify "zoomScale" property, orientation is restored.
How can I keep both orientation both zoomScale?
I suppose I need to do something in scrollView delegate:
- (void)scrollViewDidZoom:(UIScrollView *)scrollView;
I just put a repo on GitHub that might help you. It is in Swift but it should do
PhotoSlideShow-Swift
I tried to answer to this question that is about difference between view.frame and view.bounds :
I've written this:
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self showPropertiesOfLabel];
self.label.transform = CGAffineTransformMakeRotation(M_PI * 0.25);
[self showPropertiesOfLabel];
}
- (void) showPropertiesOfLabel {
NSLog(#"bounds.origin.x: %f", self.label.bounds.origin.x);
NSLog(#"bounds.origin.y: %f", self.label.bounds.origin.x);
NSLog(#"bounds.size.width : %f", self.label.bounds.size.width);
NSLog(#"bounds.size.height: %f", self.label.bounds.size.height);
NSLog(#"frame.origin.x : %f", self.label.frame.origin.x);
NSLog(#"frame.origin.y : %f", self.label.frame.origin.y);
NSLog(#"frame.size.width : %f", self.label.frame.size.width);
NSLog(#"frame.size.width : %f", self.label.frame.size.height);
}
But what's stroked me was the fact that my view that I called "label" after
self.label.transform = CGAffineTransformMakeRotation(M_PI * 0.25);
dissapeared! But still reporting it's frame and bounds values (rather appropriately).
The most interesting part is that if I changed angle of rotation :
self.label.transform = CGAffineTransformMakeRotation(M_PI * 0.26);
It works as it should. The view don't disappear anymore!
I've test it both on the device as in the simulator:
Here is the video of it, testing in simulator:
http://youtu.be/O6aYRt_4xsE
PS:
It looks for me like a bug.
EDIT:
It looks like this behavior (bug?) is caused by Autolayout mechanisms.
You can turn it OFF by clicking at your storyboard file and at the right of Xcode there should be tab
"Show the file inspector" and uncheck this box:
Here is video proving that this is in fact problem with Autolayout:
http://youtu.be/HbFRlXtiZ-g
But this still don't answer the question.
As far as I know, the results of using "classic" approaches to alter content of view hierarchies which are subject to autolayout is more or less undefined.
So this is not actually a bug. What you need to do if you would like to change your layout progammatically, is to translate your changes into changes of the autolayout constraints. This can be done automatically by setting translatesAutoresizingMaskIntoConstraints to YES.
Please have a look at this SO Question as well!
I have a pageable UIScrollView which contains different kind of informations like UITables but also zoomable images. Therefore I set up a pageable main-ScrollView and as subviews I added zoomable image-ScrollViews with the images as content.
Works everything fine, just I fail to set the smaller current zoom scale of the imageScrollViews.
UIImageView *imageView = [[UIImageView alloc] initWithImage:Image];
//storing a link to the imageView
[imagelinkArray addObject:imageView];
CGRect ScrollViewImageRect;
ScrollViewImageRect = CGRectMake((self.scrollView.frame.size.width) * i, 0, 320, self.scrollView.frame.size.height);
float widthfactor = ScrollViewImageRect.size.width / imageView.frame.size.width;
float heightfactor = ScrollViewImageRect.size.height / imageView.frame.size.height;
float zoomscale = MIN(widthfactor, heightfactor);
UIScrollView *imageScrollView = [[UIScrollView alloc] initWithFrame:ScrollViewImageRect];
imageScrollView.contentSize = CGSizeMake(imageView.frame.size.width, imageView.frame.size.height);
imageScrollView.delegate = self;
[imageScrollView setMinimumZoomScale:zoomscale];
[imageScrollView setMaximumZoomScale:1.5];
[imageScrollView addSubview:imageView];
//doesn't work:
[imageScrollView setZoomScale:0.5 animated:YES];
[self.scrollView addSubview:imageScrollView];
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return [imagelinkArray objectAtIndex:page];
}
The main-ScrollView and the image-ScrollViews are drawn perfectly and it's possible to zoom and page properly. The minimum zoom factor is calculated also correct. When I zoom out I can zoom until the image limits are reached. However the first time I page to the image-ScrollView it's current zoom scale is always 1.0 while it should be the minimum scale.
Wherever I set the zoom scale in the code above it doesn't work:
[changeScrollView setZoomScale:changeScrollView.minimumZoomScale animated:YES];
If I log the current zoom scale i always get 1.0;
The only thing which works is changing the zoom scale in the - (void)scrollViewDidScroll: method, which of course doesn't help a lot since zooming also calls it which resets the zoom immediately. But at least I could figure out, that the code somehow works. I have the feeling a UIScrollView doesn't zoom when it's not visible on the screen right now. How can I fix this?
Update:
Okay. In the meantime I figured out that the problem most likely comes from my base layout of "sub-viewing" ScrollViews into another ScrollView. When I zoom one of the images and log the current zoom factor of the ScrollViews they are all the same (main ScrollView as well as ALL sub-ScrollViews).
What could be the reason for it or how could I solve it with a different layout?
I think viewForZoomingInScrollView: may not be getting called by the scrollview. Try to add a breakpoint and check what you're returning there.
Your code doesn't work because you havent set minimumZoomScale ,which has default value of 1.0 . Since you are trying to set 0.5 which is below the default value, it wouldn't work.
Add following line just after the line which sets maximumZoomScale.
[imageScrollView setMinimumZoomScale:0.25];
As user Rivera pointed out the return value of viewForZoomingInScrollView: was off course not right.
I always returned the current visible page shown in the scrollView. Which means setting the zoom in viewDidAppear doesn't change anything.
Here is the correct code: I made a function which will always resets both images left and right of the current visible scroll page:
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
[self updateImageSize];
}
- (void)updateImageSize
{
updatePage = updatePage + 1;
if (updatePage < imagescrolllinkArray.count) {
UIScrollView *changeScrollView = (UIScrollView*)[imagescrolllinkArray objectAtIndex:updatePage];
[changeScrollView setZoomScale:changeScrollView.minimumZoomScale];
}
updatePage = updatePage - 2;
if (updatePage > -1) {
UIScrollView *changeScrollView = (UIScrollView*)[imagescrolllinkArray objectAtIndex:updatePage];
[changeScrollView setZoomScale:changeScrollView.minimumZoomScale];
}
//reset to current view
updatePage = updatePage + 1;
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return [imagelinkArray objectAtIndex:updatePage];
}
and in viewDidAppear I added the following to update the first image before any dragging.
if (i == 1) {
updatePage = 0;
[imageScrollView setZoomScale:imageScrollView.minimumZoomScale];
}
In the meantime I figured out that the code below can under certain circumstances make problems. Sometimes when I zoom in and out from an image the main ScrollView can't be scrolled anymore, so there is no way to get to the next image, except of triggering the pageControl or except of zooming into the image and then scrolling to its borders so the main ScrollView jumps to the next page.
Means the problem only occurs when the image is fully zoomed out (.scale = .minimumscale). I don't understand exactly when and why it happens. Logging viewDidScroll returns nothing in this situations.
Anybody experienced similar problems?
I tried to move a ball image in viewDidLoad as below. I ran it. The Log showed the x value changed from 160 to 50 as I expected. However, the image on the iOS Simulator is still on the original position from the Interface Builder in which x is 160. Why?
And how can I move the location of the image before it shows on the screen?
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSLog(#"%f", Ball.center.x);
Ball.center = CGPointMake(50, 50);
NSLog(#"%f", Ball.center.x);
}
Instead of viewDidLoad add your code to viewDidLayoutSubviews method
- (void)viewDidLayoutSubviews {
[super viewDidLayoutSubviews];
Ball.center = CGPointMake(50, 50);
}
Call [self.view setNeedsDisplay]; method , since your viewDidLoad triggers after the view is actually loaded and drawn on the device , and you changing the image location you should tell your device to redraw the view with a new image position.
A couple of suggestions:
1. First check that `Ball` is connected to IBOutlet in interface builder.
2. To change the frame of a UIImageView, I would suggest to use UIView animation
blocks for smooth animation effects
3. You can also use `performSelector` and delay the animation to e.g., `0.1` sec etc.
Hope these point can guide you to resolve this issue.