I don't know if this makes sense at all. I have UIScrollView from interface builder hooked it up as an outlet on top of my UIScrollView I have a UIImage view which holds an image called Scroll Background it is an extra half in screen real estate - my app is landscape and the image is an about half the screen taller. The image is hooked up as an outlet too. I have a button on a toolbar that brings up the keyboard when the button is pressed I'd like to programmatically scroll to the bottom of the UIImage view and when it is resigned I'd like to programmatically scroll to the top. I don't want the user to be able to scroll just for the app to scroll programmatically.
I can't seem to get this method to work and I'm not sure why :/
- (void)scrollRectToVisible:(CGRect)rect animated:(BOOL)animated
scrollRectToVisible:animated: is a non-intuative method to use in my opinion. In order to accomplish what you are after you should be able to set userInteractionEnabled to NO on the UIScrollView that will prevent users from scrolling.
Then in order to scroll the view programmatically you can call scrollRectToVisible but you need to give it a CGRect that is representative of the area you want to show. So in your case to scroll to the top:
CGRect visibleFrame = CGRectMake(0, 0, CGRectGetWidth(self.view.bounds) , CGRectGetHeight(self.view.bounds));
[self.myScrollView scrollRectToVisible:visibleFrame animated:YES];
Hope this helps!
Related
I have a UIViewController that displays a form with several text fields. In order to prevent the text fields from getting blocked by the keyboard, I resize the controller's view when the keyboard appears and disappears.
However, when the keyboard is up, the user presses the home button, and then returns to the app, the controller's view will be resized again to the size it was before the keyboard was up and the keyboard will still be showing.
What's causing my controller's view to be resized on return from background, and how can I prevent it?
Maybe you need to nest a UIView，for example
_backgroundView = [UIView new];
_backgroundView.backgroundColor = [UIColor whiteColor];
_backgroundView.frame = CGRectZero;
[self.view addSubview:_backgroundView];
[_backgroundView mas_makeConstraints:^(MASConstraintMaker *make) {
make.left.right.top.mas_equalTo(self.view);
make.height.mas_equalTo(self.view.mas_height);
}];
then you need add your custom UIView to this backgroundView.
as you said，UIViewController's view will be resized after return from background. so you can nest a UIView of the same size as self.view，and add your custom UIView to this UIView.
In order to prevent the text fields from getting blocked by the keyboard, you can resize this backgroundView when the keyboard appears and disappears. and this time when you click the home button to enter the background or return from background，self.view won't be resized and backgroundView won't be resized too.
Although it is a bit of a hassle, this will solve your problem and will not affect the user experience anymore. And if you have a better solution, please let me know
It sounds like you are setting the frame and not using autolayout. When the view reappears viewDidLayoutSubviews gets called and your frame gets recalculated obliterating your previous change. You can either:
1) Move your frame to viewDidLayoutSubviews and change its size only if the keyboard is showing.
2) Use autolayout and simply pull up your bottom constraint .constant by an amount equal to your keyboard height.
In both cases you should call layoutIfNeeded to trigger autolayout/viewDidLayoutSubviews when the keyboard appears/disappears. This behavior is a good example of why you should not manipulate your frames outside of viewDidLayoutSubviews except for transitory animations.
I have a quite regular UIViewController that is a part of a UINavigationController-hierarchy, which naturally makes the view have a UINavigationBar at the top. As we all know, iOS7's navigation bars are very different from previous versions.
If I drag a UITableView into my view in Storyboard, then the 'frame' for the table view is covering the entire view (I.E [tableView setFrame:self.view.frame];). Even behind the NavigationBar.
This makes so that if I scroll, the content will be faintly visible through the bar.
Contrary to most people, I actually like this.
In my current view controller, I would like to create the UITableView programmatically and place it as a subview here. However, I am unable to achieve the same effect this way.
I have tried
UITableView *table = [[UITableView alloc] initWithFrame:self.view.frame];
[self.view addSubview: table];
This makes the 'top scrolling point' stay behind the navigation bar. Imagine a single cell in a tableView, and it's faintly visible through the top bar. If I scroll down, it pops right up behind it. That's the default 'top position'.
I have also tried
CGRect frame = CGRectMake(0, 'nav.y+nav.height', self...width, self...height-y);
UITableView *table = [[UITableView alloc] initWithFrame:frame];
[self.view addSubview: table];
to simply place the table view in the rect below the UINavigationBar, but then I won't get the scrolling transparency effect behind the bar.
I also tried the first example along with this:
[tableView setContentOffset:CGPointMake(0, 'below navbar')];
which makes it stay exactly where I want it to stay, but as soon as I touch it (scroll and release), it scrolls back up behind the navigation bar, and stays there.
What's the programmatic solution to achieve this effect? Do I have to set the offset every time I scroll too far up, or is there a simpler solution? Along with this iOS7-style, I'd imagine they would add something like [tableView setVisibleFrame:] or something..?
Add the table in storyboard like normal but make sure you have it connected to an outlet (we will call it _tableView for now).
Then in your view controller's -viewDidLoad set the top inset to be the status bar plus the navigation bar:
`self.tableView.contentInset = UIEdgeInsetsMake( (self.navigationController.navigationBar.frame.origin.y + self.navigationController.navigationBar.frame.size.height), 0, 0, 0);'
This will make sure that all of the cells will be visible but will also fill the area behind the navigation bar with white so the bar doesn't end up gray.
I have a storyboard in which I have a view controller, (InfoViewController) in which I have an UIScrollView with some labels, uitextviews, etc. this is all created in IB, no code has been written at all. The only thing that is left for me to do is to set the content size, which I do as following:
-(void)viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];
CGRect screenRect = [[UIScreen mainScreen] bounds];
[self.scrollView setContentSize:CGSizeMake(screenRect.size.width, 600)];
[self.scrollView setBackgroundColor:[UIColor greenColor]];
}
Whenever I make this view the entry point of my app, it works perfectly. I can see my view, the content size is set, the background color is being set to green.
Now it comes, I created another view controller, and this view controller is now my entry point of the app. I added a button in there, and on this button I did a "modal segue" to the earlier mentioned Info View Controller.
When I now run my app, I press this button, my Info View Controller shows up. The green background color is being set, but it's impossible to scroll. So the code is being executed (otherwise the background color couldn't been green, in the storyboard it's just plain white) but somehow whenever I use this "modal segue", the scroll functionality gets lost.
How can I fix this?
Try to insert a UIView into the scroll view...
Set the UIView with top, bottom, leading and trailing space to super view to 0.
Then insert everything into the UIView rather than into the ScrollView
Then modify the constraint height of the inner UIView instead of the contentsize of the scroll view, it works with iOS7
I have an iphone app with 2 ViewControllers . Both screens(viewcontrollers) show a loading screen. I create the loading screen programmatically:
UIView *loadingScreen = [[UIView alloc] initWithFrame:CGRectMake(100,200,144,144)];
loadingScreen.center = CGPointMake(self.view.frame.size.width / 2.0, self.view.frame.size.height / 2.0);
//{.. Other customizations to loading screen
// ..}
[self.view addSubview:loadingScreen];
For some reason, the second viewcontroller's loadingScreen is significantly lower and it isn't centered on the screen. The first viewcontroller works perfectly and is dead center like I want.
The second viewcontroller is a UITableView and it shows the uinavigationbar, whereas the first viewcontroller doesn't show the uinavigationbar. Also, I use storyboard for my app.
I've outputted to the NSLog self.view.frame.size.height and loadingScreen.center in both instances and THEY HAVE THE SAME COORDINATES! So, not sure why it is showing up lower. Any ideas why the second loadingScreen is lower and how to fix? Thanks!
You mention that one screen displays a UINavigationBar while the other does not. When you display a navigation bar, it offsets the rest of your view - in this case by shifting it down.
There are two quick fixes. You can either adjust your center point up by the size of the UINavigationBar (65 pts - unless it's a custom UINavigationBar and you've changed its size) or you can set the "Adjust Scroll View Insets" value to false in the attributes inspector.
The latter is probably the easiest and comes most recommended. Note though, that the top of your UITableView will now be underneath the UINavigationBar.
My final note would be that if you wanted to do it programmatically than in your UITableView's delegate you can call
- (BOOL)automaticallyAdjustsScrollViewInsets
{
return NO;
}
I get a weird interface bug with my UIScrollView and I cant figure out how to solve it. I only wrote one line of code (shown below) and it is a blank project's setup easily reproducible!
Setting:
I have a UIScrollView that contains a UISegmentedControl (since the segments of
the control are loaded dynamically, it could exceed the width of the screen and the scrollView is supposed to scroll the segmentedControl horizontally, the height of the scrollview is the same as the UISegmentedControl's).
The ViewController that contains this is embedded in a tabBar (or navigation bar, which also shows the bug). The whole thing is using Auto-Layout.
Bug:
When I scroll the SegmentedControl some degree to the right and then switch the viewController by clicking the other tab on the tabBarController, the content-offset of the segmented control gets weirdly shifted when switching back to the initial viewcontroller. When I try to scroll to the leftmost part of the scrollview it won't let me. When switching the tabs a couple of times, it gets fixed again and I can do this over.
What I did (can you reproduce this?):
Create a blank single-view ios project
Embed the already given viewController in a tabbarcontroller.
Put a scrollView on the upper portion of the view that fits the screen from left to right.
Put a UISegmentedControl on the topleft corner of the scrollview and drag the scrollview to fit the segmented controls height height
Change the Segmented control's width a bit so xcode adds a width-constraint. in the segmented control's width constraint change the width constraint's relation to "greater than or equal"
create an outlet to the segmented control
in viewDidload add this code
[self.segmentedControl insertSegmentWithTitle:#"A really long title so it you have to scroll to see it" atIndex: 0 animated: NO];
Create a blank viewcontroller and add it as a second viewController for the tabbarController.
This is how my storyboard looks like:
Now run the project, scroll the segmented control to it's right end as far as it goes. Switch the tab and switch back and please tell me how your scrollview now behaves - and WHY.
My guess would be it has something to do with Auto Layout maybe? Can't figure out what though.
I tried fixing this by setting the scrollView's contentSize in viewDidAppear or changing the content offset of the scrollView in viewDidAppear or changing frames, combination of those and what not....
Extra question:
Is it no longer neccessary to set the scrollViews contentSize property? Why does it scroll the content automatically?
After googeling I found the answer in another StackOverflow question.
What you need to do is save the scrollview.contentOffset on viewWillDisappear,
set it to CGPointZero on viewDidDisappear and set it back to the saved state on viewDidLayoutSubviews:
-(void) viewWillDisappear: (BOOL) animated {
self.lastContentOffset = self.scrollView.contentOffset;
[super viewWillDisappear: animated];
}
-(void) viewDidDisappear:(BOOL)animated {
[super viewDidDisappear: animated];
self.scrollView.contentOffset = CGPointZero;
}
- (void)viewDidLayoutSubviews {
[super viewDidlayoutSubviews];
self.scrollView.contentOffset = self.lastContentOffset;
}