I have a content size 1000x10000 and it's center is on the center of the viewcontroller.
I want to push a button for it to turn pages. In the next code I've tried almost any number in the origin.x but nothing changes the scroll view.
I don't understand the math of it but when I set origin.x=300 and origin.y=100 the view will move up a bit but that's it.
CGRect frame=scroller.frame;
frame.origin.x=ANY NUMBER HERE;
frame.origin.y=0;
[scroller scrollRectToVisible:frame animated:YES];
How can I set it to move the view from right to left
Try this,
[scroller setContentOffset:CGPointMake(300, 0) animated:YES];
setContentOffset:animated:
Sets the offset from the content view’s origin that corresponds to the receiver’s origin.
You should be creating the UIScrollView's frame to the size of the UIViewController like so:
UIScrollView *scroller = [[UIScrollView alloc] initWithFrame:self.view.frame];
Then set the scrollers CONTENT VIEW to the 1000x10000 size like so:
scroller.contentSize = CGSizeMake(1000, 10000);
The contentSize is what makes a UIScrollview able to scroll, as long as the contentsize is larger than the scrollers frame.
If you want to make it scrollable, then contentSize has to be greater than frame.size, otherwise there isn't space to scroll.
Then ensure that scrollEnabled is set to YES (by default it is, so unless that you've changed it it's already set to YES).
Related
I have five UIView on a UIScrollView. All of them with the same width. Each view has other subviews that resize its height according to the content assigned, thus making the parent UIView and the UIScrollView resizable as well. I am trying to keep the 5 UIView separated from each other at a certain "Padding" distance even after resizing. What I do right now is set the position of the origin.y and the height of each UIView when layoutSubviews is called. Is there an easier way to do this?
I have tried to set their position on creation like: CGRectMake(0, aboveView.frame.origin.y + aboveView.frame.size.height + Padding, width, 0) and setting its autoresizingMask to UIViewAutoresizingMaskTopMargin. Hoping that when I call sizeToFit on the main UIView, all the UView will set their positions relative to the view above them.
Overriding layoutSubviews is the right way to do this. UIKit doesn't have any built-in layout management that can do it for you.
However, you might not realize that UIScrollView sends itself layoutSubviews each time it scrolls - on every frame of the scrolling. That may be a lot more often than you need! You don't want to do a lot of work in a UIScrollView's layoutSubviews if you can avoid it.
To avoid doing extra layout, I suggest you set up your view hierarchy like this:
UIScrollView
ContainerView with layoutSubviews method
content view 1
content view 2
content view 3
content view 4
content view 5
Use a standard UIScrollView. Give it one subview, which is a custom UIView subclass (I called it ContainerView in my example). The ContainerView has your five content views as its subviews.
When you assign new content to one of your five content views, send sizeToFit to that content view. If the view's size changes, UIKit should automatically send layoutSubviews to its superview - the ContainerView. The ContainerView's layoutSubviews method adjusts the position of its subviews to maintain the padding between them, and then sets the contentSize of its parent - the UIScrollView.
- (void)layoutSubviews {
CGRect myFrame = CGRectZero;
for (UIView *subview in self.subviews) {
CGRect frame = subview.frame;
if (myFrame.size.height > 0) {
frame.origin.y = myBounds.size.height + Padding;
subview.frame = frame;
}
myFrame = CGRectUnion(myFrame, frame);
}
self.frame = myFrame;
UIScrollView *scrollView = self.superview;
scrollView.contentSize = myFrame.size;
}
This way, you don't do any extra work just because the scroll view scrolled. You only lay out your content views when the content actually changes.
I'm placing a UIImageView inside of a UIScrollView, basing my code off of the answer in this question. The problem I'm having is that there is a significant amount of white space to the bottom and right, and I can't scroll to some of the image in the top and left. I figure this is due to me incorrectly setting the contentSize of the scrollView. Here's the relevant code:
- (void)viewDidLoad
{
[super viewDidLoad];
_imageView.image = _image;
_imageView.bounds = CGRectMake(0, 0, _imageView.image.size.width,_imageView.image.size.height);
_scroller.contentSize = _imageView.image.size;
}
The view controller I'm in has three properties, a UIScrollView (_scroller), a UIImageView (_imageView), and a UIImage (_image).
You're setting the UIImageView's bounds property. You want to be setting its frame property instead. Setting the bounds will resize it around its center point (assuming you haven't changed the underlying CALayer's anchorPoint property), which is causing the frame origin to end up negative, which is why you can't see the upper-left.
_imageView.frame = CGRectMake(0, 0, _imageView.image.size.width, _imageView.image.size.height);
Alternate syntax:
_imageView.frame = (CGRect){CGPointZero, _imageView.image.size};
I've a Storyboard with a UIScrollView which contains two UILabels, a UIImageView and a UITextView. The content of the UIImageView and UITextView is dynamic and so are their height.
Currently I'm doing this inside my viewDidLoad to adjust the size of the UITextView after the dynamic text is inserted:
CGRect frame = self.textView.frame;
frame.size.height = self.textView.contentSize.height;
self.textView.frame = frame;
Is this the way to change its height?
My next problem is to set the content size for the UIScrollView, to activate the scrolling. Is there a smart way to get the height of all its content or do I have to calculate the height for each element and set the sum of this as the content size of the UIScrollView?
IF you had no space in between your objects, you could make a for loop in your scrollView.subviews and add up all the heights to set as the contentSize.
As you probably don't have everything tight together, you're probably better by getting the bottom most object and adding up it's frame.origin.y and it's frame.size.height (maybe you want to have some extra space in here, but that's up to you) and that will give you your contentSize.height to keep everything in there.
I have two instances of NSScrollView both presenting a view on the same content. The second scroll view however has a scaled down version of the document view presented in the first scroll view. Both width and height can be individually scaled and the original width - height constraints can be lost, but this is of no importance.
I have the synchronised scrolling working, even taking into account that the second scroll view needs to align its scrolling behaviour based on the scaling. There's one little snag I've been pulling my hairs out over:
As both views happily scroll along the smaller view needs to slowly catch up with the larger view, so that they both "arrive" at the end of their document at the same time. Right now this is not happening and the result is that the smaller view is at "end-of-document" before the larger view.
The code for synchronised scrolling is based on the example found in Apple's documentation titled "Synchronizing Scroll Views". I have adapted the synchronizedViewContentBoundsDidChange: to the following code:
- (void) synchronizedViewContentBoundsDidChange: (NSNotification *) notification {
// get the changed content view from the notification
NSClipView *changedContentView = [notification object];
// get the origin of the NSClipView of the scroll view that
// we're watching
NSPoint changedBoundsOrigin = [changedContentView documentVisibleRect].origin;;
// get our current origin
NSPoint curOffset = [[self contentView] bounds].origin;
NSPoint newOffset = curOffset;
// scrolling is synchronized in the horizontal plane
// so only modify the x component of the offset
// "scale" variable will correct for difference in size between views
NSSize ownSize = [[self documentView] frame].size;
NSSize otherSize = [[[self synchronizedScrollView] documentView] frame].size;
float scale = otherSize.width / ownSize.width;
newOffset.x = floor(changedBoundsOrigin.x / scale);
// if our synced position is different from our current
// position, reposition our content view
if (!NSEqualPoints(curOffset, changedBoundsOrigin)) {
// note that a scroll view watching this one will
// get notified here
[[self contentView] scrollToPoint:newOffset];
// we have to tell the NSScrollView to update its
// scrollers
[self reflectScrolledClipView:[self contentView]];
}
}
How would I need to change that code so that the required effect (both scroll bars arriving at an end of document) is achieved?
EDIT: Some clarification as it was confusing when I read it back myself: The smaller view needs to slow down when scrolling the first view reaches the end. This would probably mean re-evaluating that scaling factor... but how?
EDIT 2: I changed the method based on Alex's suggestion:
NSScroller *myScroll = [self horizontalScroller];
NSScroller *otherScroll = [[self synchronizedScrollView] horizontalScroller];
//[otherScroll setFloatValue: [myScroll floatValue]];
NSLog(#"My scroller value: %f", [myScroll floatValue]);
NSLog(#"Other scroller value: %f", [otherScroll floatValue]);
// Get the changed content view from the notification.
NSClipView *changedContentView = [notification object];
// Get the origin of the NSClipView of the scroll view that we're watching.
NSPoint changedBoundsOrigin = [changedContentView documentVisibleRect].origin;;
// Get our current origin.
NSPoint curOffset = [[self contentView] bounds].origin;
NSPoint newOffset = curOffset;
// Scrolling is synchronized in the horizontal plane so only modify the x component of the offset.
NSSize ownSize = [[self documentView] frame].size;
newOffset.x = floor(ownSize.width * [otherScroll floatValue]);
// If our synced position is different from our current position, reposition our content view.
if (!NSEqualPoints(curOffset, changedBoundsOrigin)) {
// Note that a scroll view watching this one will get notified here.
[[self contentView] scrollToPoint: newOffset];
// We have to tell the NSScrollView to update its scrollers.
[self reflectScrolledClipView:[self contentView]];
}
Using this method the smaller view is "overtaken" by the larger view when both scrollers reach a value of 0.7, which is not good. The larger view then scrolls past its end of document.
I think you might be approaching this in the wrong way. I think you should be getting a percentage of how far down each scroll be is scrolled in relation to itself and apply that to the other view. One example of how this could be done is this way using NSScroller's -floatValue:
NSScroller *myScroll = [self verticalScroller];
NSScroller *otherScroll = [otherScrollView verticalScroller];
[myScroll setFloatValue:otherScroll.floatValue];
I finally figured it out. The answer from Alex was a good hint but not the full solution as just setting the float value of a scroller doesn't do anything. That value needs translation to specific coordinates to which the scroll view needs to scroll its contents.
However, due to differences in size of the scrolled document view, you cannot just simply use this value, as the scaled down view will be overtaken by the "normal" view at some point. This will cause the normal view to scroll past its end of document.
The second part of the solution was to make the normal sized view wait with scrolling until the scaled down view has scrolled its own width.
The code:
// Scrolling is synchronized in the horizontal plane so only modify the x component of the offset.
NSSize ownSize = [[self documentView] frame].size;
newOffset.x = MAX(floor(ownSize.width * [otherScroll floatValue] - [self frame].size.width),0);
The waiting is achieved by subtracting the width of the scroll view from the width times the value of the scroller. When the scaled down version is still traversing its first scroll view width of pixels, this calculation will result in a negative offset. Using MAX will prevent strange effects and the original view will quietly wait until the value turns positive and then start its own scrolling. This solution also works when the user resizes the app window.
After creating a custom view and assigning it to the navigationItem.titleView property it is displayed like this
with the custom view filling the space between the two buttons. Therefore, the custom view is not centered on the navigation bar. How do I determine the frame of the view in the .titleView property? I want to center some text in the navigation bar, say under the time stamp.
If you really want to get titleView's frame (in your top-level view's coordinate space), you can do this:
[self.navBar layoutIfNeeded];
CGRect titleViewFrameInTopLevelViewSpace = [self.navigationItem.titleView
convertRect:self.navigationItem.titleView.bounds
toView:self.view];
You need to do layoutIfNeeded if you have just assigned titleView, because by default the navigation bar won't lay out its subviews until the next pass through the run loop.
That said, the titleView will be centered automatically, if it fits. I think you are setting the frame (or bounds) of your custom view too large. I tested this two ways:
I set up the titleView directly in the XIB. I simply dragged a View from the Object library onto the center of the navigation bar:
It sized the view to 128x33 automatically. The resize handles let me adjust the size. It stays centered until it overlaps the Categorize button. Then it shifts left.
I set the titleView property in viewDidLoad:
- (void)viewDidLoad
{
[super viewDidLoad];
UIView *customView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 50, 33)];
customView.backgroundColor = [UIColor greenColor];
self.navItem.titleView = customView;
}
The result looks like this:
You could get the width of the leftBarButtonItem and the rightBarButtonItem after you've set them, and then use that to determine how to centre within the view you supply to titleView. That might do what you want?