Just started exploring Cocoa so pretty much a total noob.
I've written a very simple game. Set it up in Interface Builder and got it working fine.
It contains a number of buttons and I'm now trying to get the buttons to display images.
To start with I'm trying to get an image displayed on just one of the buttons which is called tile0 .
The image file (it's nothing but a green square at the moment, but I'm just trying to get that working before I attempt anything more exotic) is sitting in the same directory as the class file which controls the game.
I have the following code sitting in my wakeFromNib method:
NSString *myImageFileName = [[NSString alloc] init];
myImageFileName = #"greenImage.jpg";
NSImage *myImage = [[NSImage alloc] initByReferencingFile:myImageFileName];
[tile0 setImage: myImage];
Trouble is, the game runs fine, but the image isn't appearing on my button.
Is there someone who could kindly tell me if I'm doing something obviously wrong?
Many Thanks.
The first problem is you allocate a string but then replace it with a string constant. That isn't causing your image problem but it is a memory leak.
I've never used initByReferencingFile, I usually just use imageNamed:. There is an example of using imageNamed here.
Related
My table view loads pictures through SDWebImage (async image downloading/cache category for UIImageView) in each tableView:cellForIndexPath:.
// 'spot' is a dictionary of this cell's attributes
NSURL* imageURL = [NSURL URLWithString:(NSString*)[spot objectForKey:#"Image"]];
UIImage* placeholderImage = [UIImage imageNamed:#"placeholder.png"];
^ Loads the images, but is constantly having to make requests or pull from the cache. So I wanted to see if the rendered cells were stored in memory, so I could only make requests for images when I need them. I went about this by adding a simple check for the image property of the image view.
if (!cell.pictureView.image)
{
NSURL* imageURL = [NSURL URLWithString:(NSString*)[spot objectForKey:#"Image"]];
UIImage* placeholderImage = [UIImage imageNamed:#"placeholder.png"];
[cell.pictureView setImageWithURL:imageURL placeholderImage:placeholderImage options:SDWebImageCacheMemoryOnly];
}
This works and keeps my images from having to reload after exiting and reentering the application. But in one of my cells that has a purposely bad image url (for debugging), the image- which used to remain as the imageNamed:#"placeholder"- is now the same image as my second cell.
I'm curious what kind of cell-reuse/cache magic is causing the cell to take the picture of a previous cell.
What is the best way to retain cell properties and only set them when needed?
It's very likely the issue is with the image package you are using. If you are making repeated URL requests to grab images, it is probably best practice to implement NSURLCache, which is a fairly simple and handles caching perfectly so it is not an issue. This is the NSHipster guide on how to use it. Other solutions tend towards these sorts of issues. Since it is a category on UIImageView, it could be any number of things causing issues with UIImageView's implementation when getting used in the cell.
I'm writing a networking program which sends an image from an iPhone to a Mac. I have the connection going fine, and passing data alright, but my problem is when I have the image sent over I try to display it and get the following warning:
NSImageView(0x101321fd0) - NSView not correctly initialized. Did you
forget to call super?
Here is the code, it's the "setImage" command throwing the error.
This is my first major venture into Objective-C, I'm worried I messed up something with the xib but I can't be sure.
imageView = [NSImageView alloc];
[imageView setImage:theImage];
NSLog(#"Should be able to see image now..");
If this is too vague for a direct answer then any tips, references or tutorials you can guide me to would be very welcome.
Thanks for your time.
You forget to init the imageView.
imageView = [[NSImageView alloc] initWithFrame:someFrame]
I am developing a complete application using the template "page-based storyboard".
But whenever I turn page, I see thru the instruments that the amount of memory allocated only increase and never decrease, so until a crash occurs.
Trying in iPad device crash too.
To simplify and try to find the problem, I created a test app using the same template and opting for ARC, only loading the image of the pages that I use and no change anything in the original apple code, even in this simple application the problem occurs.
I think the problem is because all page are stay allocated like this issue
PageViewController: How to release ViewControllers added to it?
but I m using storyboard, so, where is:
PageView *pView = [[PageView alloc] init];
I have:
MWViewController *dataViewController = [storyboard instantiateViewControllerWithIdentifier:#"MWDataViewController"]
I try to put autorelease but no effect.
The problem that I was having is that I was using background image in all pages and the imageNamed: method caches images which makes my memory footprint grow. I used the UIImage initWithContentsOfFile: method and my foot print stayed mostly flat.
I'm loading a very big file in an NSimage with this code :
[[NSImage alloc] initWithContentsOfFile:aFile]
This operation take a few time. I want to display the loading status on my UI.
How can it's possible to read or calculate a progression ?
Thanks.
Initialize the image by referencing the file, which will not load it immediately. Then, set yourself as the image's delegate and respond to the incremental-loading messages that are part of the NSImageDelegate protocol. Then, attempt to ask the image for some information about itself (asking for its representations would probably be a good way), to cause the image to start loading.
I think this will still block your UI, though: You'll be able to display progress, but not to enable the user to work on other things while the image loads. I'm not sure how you would do that.
I am having a problem that is eating me alive. I really hope I am just missing something small here. It appears to be a rather "n00b" issue.
I have a blank NSImageView that I want to display a picture when a button is pressed — simple as that.
Here is my line of coding
NSBundle *mb = [NSBundle mainBundle];
NSString *fp = [mb pathForResource:#"tiles" ofType:#"PNG"];
NSImage *image = [[NSImage alloc] initWithContentsOfFile:fp];
if ( [image isValid] ) {
[selection setImage:image];
[selection setImageScaling:NSScaleProportionally];
}
Whereas,
tiles.PNG is a resource in my bundle
and if [image isValid] is satisfied, because I've inserted dummy code into the clause and had that work
selection is defined in my header file as follows
IBOutlet NSImageView *selection;
It is also linked up to the application delegate in IB.
I have a feeling I might not be linking it properly?
WHy wouldn't the image display? If anyone can see an error - or provide me with working code - I would be soooooo thankful
Brian
It's not a linking issue—your app wouldn't even launch (assuming it even links successfully) if you'd failed to link against Cocoa or AppKit.
More probably, either you haven't connected the outlet to your image view in your nib, or you haven't loaded the nib yet. The way to check this would be to NSLog the value of the imageView pointer, using the %p formatter.
I had a similar issue where my view wasn't displaying, and it turned out that the view was hidden. This was a setting in the view properties in Interface Builder. Just a punt, but give it a go.
You need to use the debugger and see what's going on as it runs. Is fp nil? Is image nil? Is selection nil? The debugger is your friend.
did you remember to send -setNeedsDisplay to the NSImageView after you set the image?