I need to resize imageview on scroll and tried some answers in stackoverflow but failed to implement those. Not sure what did I missed, please advice.
-(void)scrollViewDidScroll:(UIScrollView *)scrollView {
int scrollY = scrollView.contentOffset.y;
if (scrollY > 0) {
_coverImgView.frame = CGRectMake(0, 23 + scrollY, 375, 139 - scrollY);
_coverImgView.center = _coverImgView.superview.center;
}
}
Sharing current configuration of my UIImageView
Also sharing UI
Let me know, your suggestions on this.
Expecting UIImageView to reduce height onscroll.
When using auto-layout you shouldn't be directly setting the frame of any of your views, you should be changing the layout constraint constants to reposition and size your views and then updating the layout.
So, change the 'top' and 'height' constraints each time the delegate method is called, then layoutIfNeeded.
Related
Using storyboard, I have placed an imageView as my tableView's headerView inside a ViewController.
This is how my storyboard is set up:
Depending on what data the user is viewing, the viewController will either show or hide the headerView. My question is, that when the headerView is visible and the user drags down on the tableView, how can I have the imageView stick to both the navigationBar and the tableView as it resizes to cover the space in between?
This is what it currently does:
But this is what I'm going for:
Any help would be greatly appreciated. I've looked at parallax libraries, but none support sectionTitles, and I'm not necessarily going for the parallax effect either. When the user scrolls up, I want it to bounce back to the regularView and not hide the headerView. Thanks!
UPDATE:
I have followed the advice posted by Dany below and have done the
following:
-(void)scrollViewDidScroll:(UIScrollView*)scrollView {
CGRect initialFrame = CGRectMake(0, 0, 320, 160);
if (scrollView.contentOffset.y < 0) {
initialFrame.size.height =! scrollView.contentOffset.y;
childHeaderView.frame = initialFrame;
} }
childHeaderView is an imageView and for some reason when I drag down,
the image moves up (like half of it behind the navBar) and doesn't return. Any advice would be
greatly appreciated!! Thanks!
I recently posted a blog post about accomplishing this using constraints which might help, turns out it was quite straight forward.
Here is the link: Creating parallax effect on UIScrollView using constraints
First of all you should remove the UIImageView from the header and add it as a simple UIImageView on top of the UITableView then since UITableViewDelegate protocol conforms to UIScrollViewDelegate protocol you can implement the scrollViewDidScroll: method to check when the tableView is scrolling down and has a bouncing effect. something like this:
-(void)someInitMethod {
initialFrame = yourHeaderView.frame;
}
-(void)scrollViewDidScroll:(UIScrollView*)scrollView {
if(scrollView.contentOffset.y < 0) {
initialFrame.size.height -= scrollView.contentOffset.y;
yourHeaderView.frame = initialFrame;
}
}
Also make sure you set the proper contentMode for your UIImageView. Also I think this implementation will create a bouncing effect but I'm not sure because I can't test it right now but I think this is a good start point for you.
This is how I achieved it, in my case I was using a map view up the top:
Create a View Controller in storyboard.
Add a Table View and set the constraints to 0 from all sides.
Add a Map View (or whatever view) below the Table View so that it will get rendered over the top. It will look like it is overlapping.
Add constraints to the top left and right.
In the view controller viewDidLoad add the following: tableView.contentInset = UIEdgeInsetsMake(200, 0, 0, 0) where 200 is the height of the View. This will push the contents of the table view downwards.
In the view controller add the following code, which resizes the view based on the scrolling:
func scrollViewDidScroll(scrollView: UIScrollView) {
var scrollOffset = scrollView.contentOffset.y
var headerFrame = mapView.frame
if (scrollOffset < 0) {
// Adjust map
headerFrame = CGRect(x: mapView.frame.origin.x,
y: mapView.frame.origin.y,
width: mapView.frame.size.width,
height: -scrollOffset)
} else {
// Adjust map
headerFrame = CGRect(x: mapView.frame.origin.x,
y: mapView.frame.origin.y,
width: mapView.frame.size.width,
height: 0)
}
mapView.frame = headerFrame
}
If I could set contentInset from the storyboard it would be even more pretty
Please have a look at this https://github.com/matteogobbi/MGSpotyViewController which implements the same effect as per your requirement.
The earlier solutions on this page gave me some trouble when I needed this to work along with section titles and index bar, so I came up with the following alternative myself. Please note; I don't use autolayout in my project and I've only tested this on iOS9+;
In your project's storyboard:
Create a UITableView within a UIViewController (or try it with a UITableViewController).
Drop a UIView at the top (but within) the UITableView, so it becomes a table header above the first cell.
Give this header view a desired height (like 200px for example) and set the background color to "Clear Color". The Clear Color is important, the view needs to be see-through.
Drop a 2nd UIView within the table header UIView and make it the same size as it's parent. This will be the actual header, so feel free to give it any color, setup an image view or other content.
Connect this 2nd UIView to your UIViewController IBOutlet, I named it "headerView" in my case.
Next, go to your UIViewController.m:
- (void)viewDidLoad
{
[super viewDidLoad];
// Remove view from table header and place it in the background instead.
[self.headerView removeFromSuperview];
UIView *backgroundView = [UIView new];
[backgroundView addSubview:self.headerView];
self.tableView.backgroundView = backgroundView;
}
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
/* Set initialScrollOffset ivar to start offset, because in my case
the scroll offset was affected by the statusbar + navigation bar heights
and the view controller's "extend edges under top bars" option. */
initialScrollOffset = self.tableView.contentOffset.y;
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
/* Modify headerView height only if the table content gets pulled
beyond initial offset. */
if (scrollView.contentOffset.y < initialScrollOffset) {
CGRect frame = self.headerView.frame;
frame.size.height = self.tableView.tableHeaderView.frame.size.height + -scrollView.contentOffset.y;
self.headerView.frame = frame;
}
}
I needed this implementation only for a stretching header with background color and labels. It should be easy to add a UIImageView to this header though.
Also, steps 1 to 5 are completely optional of course. You can programmatically create your header view or use a XIB instead. As long as you make sure the table has a Clear Colored header view set with the same height as your desired header because this serves as a spacer to keep your cells and section titles in line.
EDIT:
I found an even cleaner way to accomplish this;
Build up your table header in interface builder as described above: 1 UIView as container with a 2nd UIView embedded within.
Skip the viewDidLoad code above, there is no need to pull the UIView out of it's container and we won't need to set it as a table background.
Change the scrollViewDidScroll: method to this:
UIViewController.m:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if (scrollView.contentOffset.y < initialScrollOffset) {
CGRect frame = self.headerView.frame;
frame.size.height = self.tableView.tableHeaderView.frame.size.height - scrollView.contentOffset.y;
frame.origin.y = self.tableView.tableHeaderView.frame.origin.y + scrollView.contentOffset.y;
self.headerView.frame = frame;
}
}
That's it. Only visual difference from the other solution is that the contents will now scroll up along with the rest of the cells instead of being overlapped by them.
I don't know, if this would help you or not ..
Set your scroll delegate to self.
and then implement this:
-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
float scrollViewHeight = scrollView.frame.size.height;
float scrollContentSizeHeight = scrollView.contentSize.height;
float scrollOffset = scrollView.contentOffset.y;
if (scrollOffset == 0)
{
// then we are at the top
}
else if (scrollOffset + scrollViewHeight == scrollContentSizeHeight)
{
// then we are at the end
// Do what you need here
}
}
In a UIViewController on a storyboard, I have a UITableView that is sized specifically to have two rows in one section with no header or footer, i.e. the height is 88.0f. There are some cases when I want to add a third row. So in viewWillAppear:animated: (and other logical places) I set the frame to be 44.0f logical pixels higher:
CGRect f = self.tableView.frame;
self.tableView.frame = CGRectMake(f.origin.x, f.origin.y, f.size.width, f.size.height + 44.0f);
NSLog(#"%#",NSStringFromCGRect(self.tableView.frame));
Nothing controversial; pretty standard resize code, and yet... It doesn't work! The tableView height doesn't change visually. The NSLog statement reports the height I expect (132.0f). Is this because I'm using Storyboards? I'm not sure why this isn't working.
Set an auto layout constraint for the height of the table view in your storyboard. Then connect the constraint to an outlet in your view controller so you can access the constraint in your code. Have the constraint be set to 88. When you want to change the height of the table view, just change the constraint's constant to 132.
You can modify the frame only after the call to layoutSubviews is made, which occurs after viewWillAppear. After layoutSubviews is called on the UIVIew you can change the dimensions.
As Gavin suggests, if you have the autolayout enabled you can add the constrains to the UITableView via storyboard, connect the height constraint and modify its value as follow:
constraint.constant = 132.0f
Otherwise if you have the autolayout disabled you can simply change the frame updating the height, but putting the code in a different method, for example viewDidLoad:.
recently I'm try to do what you've do. And I got same problem, tableview height won't change. Now I got the solution, you need to call layoutSubviews after change the frame. And it work on me.
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
tableView.frame = CGRectMake(tableView.frame.origin.x, tableView.frame.origin.y, tableView.frame.size.width, tableView.frame.size.height + 44.);
[tableView layoutSubviews];
}
don't place it in viewDidLoad or viewWillAppear: because even layoutSubviews is called, the frame won't change. place it on viewDidAppear:
Sorry for the bother but I'm trying to lazy load several imageViews and then resize it proportionately to the content in a UITableView. I'm also trying (Unwisely perhaps?) to use Autolayout basically for the first time. And I'm not understanding why the constraints aren't working in this case. Here's the code that I'm using to resize the UIImageView after I've loaded the proper image into it.
// Scale the image view and return it.
- (UIImageView *) scaleImageViewForScreenWidth:(UIImageView *)imageView {
UIImage *imgFromView = [imageView image];
CGRect newFrame = CGRectMake(0, 0, imgFromView.size.width, imgFromView.size.height);
float imgFactor = newFrame.size.height / newFrame.size.width;
newFrame.size.width = [[UIScreen mainScreen] bounds].size.width;
newFrame.size.height = newFrame.size.width * imgFactor;
[imageView setFrame:newFrame];
return imageView;
}
As far as constraints are concerned. I'm trying to attach a Label and UIImageView with a shadow to the bottom of the main imageview. Here are the constraints that I'm applying to a bottom shadow in the imageview. The bottom shadow constraints are:
Height Equals: 83
Align Bottom to: Background Image View
LeadingSpace to: Table View Cell
I'm not getting what I want though. Any ideas? I feel like I'm fighting autolayout.
As requested! Here's some guidelines for using Autolayout that should help a lot.
The first thing is that the ideal approach is for you to set things up in Interface Builder so that no further programming is required. So, if - for example - the bounds of your view change, then your view will adjust itself automatically as required.
If that doesn't do the business, then you may have to update the constraints programmatically. Now, the golden rules as I mentioned is that you update the constraints. Resist the temptation to update the underlying UIView frame!
So, you'll do something like:
_myWidthConstraint.constant = 300.f;
The next thing to note is that you should do this in a specific place, and that is in your UIView subclass method updateConstraints:
- (void)updateConstraints
{
[super updateConstraints];
_myWidthConstraint.constant = 300.f;
}
How do you trigger that? By invoking:
[self setNeedsUpdateConstraints];
Hope this helps! For further info check Ole Begemann's excellent article 10 Things You Need To Know About Cocoa Autolayout.
Don't forget the WWDC videos. These are essential!
Also, now there's a book iOS Auto Layout Demystified . Although I've bought it, I haven't had a chance to read it yet. It does look pretty good though.
I was also facing the same issue. the image inside the imageview was too big for the imageview and the contentMode was set to AspectFill.
I solved this by unchecking 'Autoresize Subviews".
Using storyboard, I have placed an imageView as my tableView's headerView inside a ViewController.
This is how my storyboard is set up:
Depending on what data the user is viewing, the viewController will either show or hide the headerView. My question is, that when the headerView is visible and the user drags down on the tableView, how can I have the imageView stick to both the navigationBar and the tableView as it resizes to cover the space in between?
This is what it currently does:
But this is what I'm going for:
Any help would be greatly appreciated. I've looked at parallax libraries, but none support sectionTitles, and I'm not necessarily going for the parallax effect either. When the user scrolls up, I want it to bounce back to the regularView and not hide the headerView. Thanks!
UPDATE:
I have followed the advice posted by Dany below and have done the
following:
-(void)scrollViewDidScroll:(UIScrollView*)scrollView {
CGRect initialFrame = CGRectMake(0, 0, 320, 160);
if (scrollView.contentOffset.y < 0) {
initialFrame.size.height =! scrollView.contentOffset.y;
childHeaderView.frame = initialFrame;
} }
childHeaderView is an imageView and for some reason when I drag down,
the image moves up (like half of it behind the navBar) and doesn't return. Any advice would be
greatly appreciated!! Thanks!
I recently posted a blog post about accomplishing this using constraints which might help, turns out it was quite straight forward.
Here is the link: Creating parallax effect on UIScrollView using constraints
First of all you should remove the UIImageView from the header and add it as a simple UIImageView on top of the UITableView then since UITableViewDelegate protocol conforms to UIScrollViewDelegate protocol you can implement the scrollViewDidScroll: method to check when the tableView is scrolling down and has a bouncing effect. something like this:
-(void)someInitMethod {
initialFrame = yourHeaderView.frame;
}
-(void)scrollViewDidScroll:(UIScrollView*)scrollView {
if(scrollView.contentOffset.y < 0) {
initialFrame.size.height -= scrollView.contentOffset.y;
yourHeaderView.frame = initialFrame;
}
}
Also make sure you set the proper contentMode for your UIImageView. Also I think this implementation will create a bouncing effect but I'm not sure because I can't test it right now but I think this is a good start point for you.
This is how I achieved it, in my case I was using a map view up the top:
Create a View Controller in storyboard.
Add a Table View and set the constraints to 0 from all sides.
Add a Map View (or whatever view) below the Table View so that it will get rendered over the top. It will look like it is overlapping.
Add constraints to the top left and right.
In the view controller viewDidLoad add the following: tableView.contentInset = UIEdgeInsetsMake(200, 0, 0, 0) where 200 is the height of the View. This will push the contents of the table view downwards.
In the view controller add the following code, which resizes the view based on the scrolling:
func scrollViewDidScroll(scrollView: UIScrollView) {
var scrollOffset = scrollView.contentOffset.y
var headerFrame = mapView.frame
if (scrollOffset < 0) {
// Adjust map
headerFrame = CGRect(x: mapView.frame.origin.x,
y: mapView.frame.origin.y,
width: mapView.frame.size.width,
height: -scrollOffset)
} else {
// Adjust map
headerFrame = CGRect(x: mapView.frame.origin.x,
y: mapView.frame.origin.y,
width: mapView.frame.size.width,
height: 0)
}
mapView.frame = headerFrame
}
If I could set contentInset from the storyboard it would be even more pretty
Please have a look at this https://github.com/matteogobbi/MGSpotyViewController which implements the same effect as per your requirement.
The earlier solutions on this page gave me some trouble when I needed this to work along with section titles and index bar, so I came up with the following alternative myself. Please note; I don't use autolayout in my project and I've only tested this on iOS9+;
In your project's storyboard:
Create a UITableView within a UIViewController (or try it with a UITableViewController).
Drop a UIView at the top (but within) the UITableView, so it becomes a table header above the first cell.
Give this header view a desired height (like 200px for example) and set the background color to "Clear Color". The Clear Color is important, the view needs to be see-through.
Drop a 2nd UIView within the table header UIView and make it the same size as it's parent. This will be the actual header, so feel free to give it any color, setup an image view or other content.
Connect this 2nd UIView to your UIViewController IBOutlet, I named it "headerView" in my case.
Next, go to your UIViewController.m:
- (void)viewDidLoad
{
[super viewDidLoad];
// Remove view from table header and place it in the background instead.
[self.headerView removeFromSuperview];
UIView *backgroundView = [UIView new];
[backgroundView addSubview:self.headerView];
self.tableView.backgroundView = backgroundView;
}
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
/* Set initialScrollOffset ivar to start offset, because in my case
the scroll offset was affected by the statusbar + navigation bar heights
and the view controller's "extend edges under top bars" option. */
initialScrollOffset = self.tableView.contentOffset.y;
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
/* Modify headerView height only if the table content gets pulled
beyond initial offset. */
if (scrollView.contentOffset.y < initialScrollOffset) {
CGRect frame = self.headerView.frame;
frame.size.height = self.tableView.tableHeaderView.frame.size.height + -scrollView.contentOffset.y;
self.headerView.frame = frame;
}
}
I needed this implementation only for a stretching header with background color and labels. It should be easy to add a UIImageView to this header though.
Also, steps 1 to 5 are completely optional of course. You can programmatically create your header view or use a XIB instead. As long as you make sure the table has a Clear Colored header view set with the same height as your desired header because this serves as a spacer to keep your cells and section titles in line.
EDIT:
I found an even cleaner way to accomplish this;
Build up your table header in interface builder as described above: 1 UIView as container with a 2nd UIView embedded within.
Skip the viewDidLoad code above, there is no need to pull the UIView out of it's container and we won't need to set it as a table background.
Change the scrollViewDidScroll: method to this:
UIViewController.m:
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if (scrollView.contentOffset.y < initialScrollOffset) {
CGRect frame = self.headerView.frame;
frame.size.height = self.tableView.tableHeaderView.frame.size.height - scrollView.contentOffset.y;
frame.origin.y = self.tableView.tableHeaderView.frame.origin.y + scrollView.contentOffset.y;
self.headerView.frame = frame;
}
}
That's it. Only visual difference from the other solution is that the contents will now scroll up along with the rest of the cells instead of being overlapped by them.
I don't know, if this would help you or not ..
Set your scroll delegate to self.
and then implement this:
-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
float scrollViewHeight = scrollView.frame.size.height;
float scrollContentSizeHeight = scrollView.contentSize.height;
float scrollOffset = scrollView.contentOffset.y;
if (scrollOffset == 0)
{
// then we are at the top
}
else if (scrollOffset + scrollViewHeight == scrollContentSizeHeight)
{
// then we are at the end
// Do what you need here
}
}
I have a UIView like iPhone's Springboard. I have created it using a UIScrollView and UIButtons. I want to disable horizontal scrolling on said scrollview. I want only vertical scrolling. How do I accomplish this?
You have to set the contentSize property of the UIScrollView. For example, if your UIScrollView is 320 pixels wide (the width of the screen), then you could do this:
CGSize scrollableSize = CGSizeMake(320, myScrollableHeight);
[myScrollView setContentSize:scrollableSize];
The UIScrollView will then only scroll vertically, because it can already display everything horizontally.
UPDATED: (After #EranMarom pointed out on his comment)
You can stop horizontal scrolling or vertical scrolling in the ScrollViewDelegate Method.
Here it is how,
Stops Horizontal Scrolling:
If you want to scroll horizontally, then you need to increase the contentOffset.x. Preventing that stops the scrollview scroll in horizontal direction.
- (void)scrollViewDidScroll:(UIScrollView *)sender {
sender.contentOffset.x = 0.0
}
Stops Vertical Scrolling:
If you want to scroll vertically, then you need to increase the contentOffset.y. Preventing that stops the scrollview scroll in vertical direction.
- (void)scrollViewDidScroll:(UIScrollView *)sender {
sender.contentOffset.y = 0.0
}
Above code prevents the changes in x and y of a scrollview contentOffset and it leads to stop the scrolling in scrollViewDidScroll: method.
since iOS7 use
self.automaticallyAdjustsScrollViewInsets = NO;
//and create you page scroller with 3 pages
self.pageView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
[self.pageView setContentSize:CGSizeMake(self.view.frame.size.width*3, self.view.frame.size.height)];
[self.pageView setShowsVerticalScrollIndicator:NO];
[self.pageView setPagingEnabled:YES];
[self.view addSubview:self.pageView];
Swift solution
Create two outlets, one for your view and one for your scroll view:
#IBOutlet weak var myView: UIView!
#IBOutlet weak var scrollView: UIScrollView!
Then in your viewDidLayoutSubviews you can add the following code:
let scrollSize = CGSize(width: myView.frame.size.width,
height: myView.frame.size.height)
scrollView.contentSize = scrollSize
What we've done is collected the height and width of the view and set the scrollViews content size to match it. This will stop your scrollview from scrolling horizontally.
More Thoughts:
CGSizeMake takes a width & height using CGFloats. You may need to use your UIScrollViews existing height for the second parameter. Which would look like this:
let scrollSize = CGSize(width: myView.frame.size.width,
height: scrollView.contentSize.height)
In my case, with Swift 4.2 you can use:
Disable vertical scroll:
func scrollViewDidScroll(_ scrollView: UIScrollView) {
scrollView.contentOffset.y = 0.0
}
Disable horizontal scroll:
func scrollViewDidScroll(_ scrollView: UIScrollView) {
scrollView.contentOffset.x = 0.0
}
In my case the width of the contentView was greater than the width of UIScrollView and that was the reason for unwanted horizontal scrolling. I solved it by setting the width of contentView equal to width of UIScrollView.
Hope it helps someone
You can select the view, then under Attributes Inspector uncheck User Interaction Enabled .
Introduced in iOS 11 is a new property on UIScrollView
var contentLayoutGuide: UILayoutGuide
The documentation states that you:
Use this layout guide when you want to create Auto Layout constraints related to the content area of a scroll view.
Along with any other Autolayout constraints that you might be adding you will want to constrain the widthAnchor of the UIScrollView's contentLayoutGuide to be the same size as the "frame". You can use the frameLayoutGuide (also introduced in iOS 11) or any external width (such as your superView's.)
example:
NSLayoutConstraint.activate([
scrollView.contentLayoutGuide.widthAnchor.constraint(equalTo: self.widthAnchor)
])
Documentation:
https://developer.apple.com/documentation/uikit/uiscrollview/2865870-contentlayoutguide
#Gulfam Khan's answer is the correct one, I am adding imagery to help the concept get more visibility.
When we set the contentView to have equal width's with the Scroll view, if the multiplier is even slightly greater than 1:1, then we will get horizontal scrolling.
Here is what it produces:
If you do not want horizontal scrolling, you most likely do not have horizontal content that exceeds the width of the superview.
Therefore if you ensure the contentView width does not exceed the width of the scroll view, that will automatically resolve the problem as UIKit recognizes there is no horizontal content to scroll to. Like so:
Now you should only see vertical:
I had the tableview contentInset set in viewDidLoad (as below) that what causing the horizontal scrolling
self.tableView.contentInset = UIEdgeInsetsMake(0, 30, 0, 0);
Check if there are any tableview contentInset set for different reasons and disable it
I struggled with this for some time trying unsuccessfully the various suggestions in this and other threads.
However, in another thread (not sure where) someone suggested that using a negative constraint on the UIScrollView worked for him.
So I tried various combinations of constraints with inconsistent results. What eventually worked for me was to add leading and trailing constraints of -32 to the scrollview and add an (invisible) textview with a width of 320 (and centered).
Try This:
CGSize scrollSize = CGSizeMake([UIScreen mainScreen].bounds.size.width, scrollHeight);
[scrollView setContentSize: scrollSize];
Disable horizontal scrolling by overriding contentOffset property in subclass.
override var contentOffset: CGPoint {
get {
return super.contentOffset
}
set {
super.contentOffset = CGPoint(x: 0, y: newValue.y)
}
}
Once I did it replacing the UIScrollView with a UITableView with only 1 cell, it worked fine.
Use this single line.
self.automaticallyAdjustsScrollViewInsets = NO;