I'm creating a UIImageView within the code and I want to get it later on and set an image. How do I do this please help?
for (int x = 1; x <= 5; x++) {
UIImageView *Game_ImageViews = [[UIImageView alloc]
initWithFrame:CGRectMake(0, 0, 100, 100)];
Game_ImageViews.tag = x;
[Game_View addSubview:Game_ImageViews];
}
UIImage *image = [[UIImage alloc] initWithContentsOfFile:[[[NSBundle mainBundle] resourcePath]
stringByAppendingPathComponent:#"Test.png"]];
(UIImageView*)[self.view viewWithTag:100].image = image;
[image release];
viewWithTag will give you the view with the tag if a subview with that tag exists. So for example, your self.view would have to have a subview that has a tag of 100.
Initially, you are setting up subviews of Game_View with tags of 1, 2, 3, 4, 5.
So, to retrieve a subview by tag you would have to do, assuming you want to retrieve the view tagged by id 1:
((UIImageView*)[Game_View viewWithTag:1]).image = image;
A couple of other things worth mentioning. You're not releasing Game_ImageViews in your loop above, so that will give a memory leak.
Also, if you use the imageNamed method of UIImage, that will give you a couple of benefits. First, you'll have a cached image which could improve performance. Secondly, you'll have an autoreleased object which saves you the bother of releasing it yourself. Unless of course you want maximum performance and control by doing it as you have done above.
Related
I want to display some images in a scroll view, but I am facing some issues.
Here is what I have:
- (void)viewDidLoad
{
[super viewDidLoad];
myObject = [[NSMutableArray alloc] init];
[myObject addObject:#"tut_5.jpg"];
[myObject addObject:#"tut_2.jpg"];
[myObject addObject:#"tut_3.jpg"];
[myObject addObject:#"tut_4.jpg"];
pageControlBeingUsed = NO;
CGRect screenRect = [[UIScreen mainScreen] bounds];
CGFloat screenWidth = screenRect.size.width;
CGFloat screenHight = screenRect.size.height;
for (int i = 0; i < [myObject count]; i++) {
CGRect frame;
frame.origin.x = self.takeTourScrollView.frame.size.width * i;
frame.origin.y = 0;
frame.size = self.takeTourScrollView.frame.size;
NSString *val = [myObject objectAtIndex:i];
UIImage* theImage = [UIImage imageNamed:val];
UIImageView *img=[[UIImageView alloc] initWithFrame:CGRectMake(screenWidth*i,0,185 ,284)];
img.image = theImage;
[self.takeTourScrollView addSubview:img];
}
The first first image seems to be ok.
Then when I swipe left I am getting a blank screen
I swipe left again and then I see my second picture. And it goes like that for all the 4 images.
Any ideas what am I doing wrong ?
There are system components that will give you what you want with much less work and a more refined user experience. Using a UICollectionView is one possibility, as mentioned by Vive in her answer. My suggestion would be a UIPageViewController. There is a sample app called PhotoScroller from Apple that shows how to implement a UI very much like what you describe. Do a search in the Xcode docs for "PhotoScroller" to find it.
I'd advise to use UITableView/UICollectionView for such behaviour. You can set the image in each cell and they'll be reused - it will be much better in terms of memory management.
The tableView will by the way place all elements in proper places (you just need to define the height of the cell or the layout).
It will also properly resize on events (eg phone rotation).
Also, you should try to avoid hardcoding the sizes:
CGRectMake(screenWidth*i,0,185 ,284)
You will fail in case of smaller / bigger devices. It'll be a great pain to maintain the code after some time.
-- edit --
After #Duncan C posted his answer, I've noticed you're looking for a paging system. You can go with building your own solution either on UIPageViewController or on UICollectionView. However you can also use third party libraries, I really enjoy this one: https://www.cocoacontrols.com/controls/bwwalkthrough. It has a support of different animations and does a ton of stuff for you :).
you already set the x position of uiscrollview. do not need to set the x postion of UIImageView.Because you used imageview as a subview of uiimagescrollview.
change this line to
UIImageView *img=[[UIImageView alloc] initWithFrame:CGRectMake(screenWidth*i,0,185 ,284)];
with
UIImageView *img=[[UIImageView alloc] initWithFrame:CGRectMake(0,0,185 ,284)];
I have a scrollView in which i load images into from the net .I sometimes get memory warnings, which i assume are because i am doing something wrong with the images loader.
I am trying to fix little things, and i just wanted to show the code here, and hear maybe there are more things i can fix to get rid of this warnings.
So every time the scroller (iPad) has only 4/5 images that are : current page-3->current page+3.
This is how i load the images(every image has also a blur effect with Apple's classes) :
(should i allocated imageView every time? can i improve something here? )
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^
{
NSData *imdata2 = [NSData dataWithContentsOfURL:url];
dispatch_async(dispatch_get_main_queue(), ^
{
UIImage *theImage=[UIImage imageWithData:imdata2 scale:1];
UIImage *LightImage = [theImage applyLightEffect];
UIImage *scaledImage =[resizer resizeImageToWidth:[Globals sharedGlobals].imagesWidth WithImage:theImage];
CGRect viewSizeBack=CGRectMake(scroller.bounds.size.width*toPage , 0, scroller.bounds.size.width, scroller.bounds.size.height);
int x=[Globals sharedGlobals].pageMargins;
int y=([UIScreen mainScreen].bounds.size.height-scaledImage.size.height)/2;
CGRect viewSizeFront=CGRectMake(x , y, scaledImage.size.width,scaledImage.size.height);
UIImageView *backImageView=[[UIImageView alloc] initWithFrame:viewSizeBack];
UIImageView *frontImageView=[[UIImageView alloc] initWithFrame:viewSizeFront];
backImageView.layer.cornerRadius = 0.0;
backImageView.layer.masksToBounds = YES;
backImageView.image=LightImage;
frontImageView.layer.cornerRadius = 0.0;
frontImageView.layer.masksToBounds = YES;
frontImageView.image=scaledImage;
frontImageView.layer.borderWidth=1.0;
frontImageView.layer.borderColor=[UIColor colorWithRed:255.0 green:255.0 blue:255.0 alpha:1.0].CGColor;
[backImageView addSubview:frontImageView];
backImageView.tag=toPage;
frontImageView.tag=toPage;
[scroller addSubview:backImageView];
});
});
You should only ever have 3 images loaded at a maximum - the previous page (if it exists), the current page and the next page.
Any other images you have loaded above this is wasteful because you can't see them and they're just taking up memory for no good reason. If the images aren't too big then you can maintain them in memory and purge them when you get a warning, but for large images this will still generally cause you issues.
If you don't use ARC then add this:
[backImageView autorelease];
[frontImageView autorelease];
Suppose I generated the 100 image views. First of all I wish to generate all 100 image views and add them in my scroll view.
So image view are clearly display it’s in position using background color
Then after I want to set images into the image view. I have to types of Dictionary (Which comes from the another class). One Dictionary into set Already Downloaded images and another one into only generate object (Remaining download images). I am downloading this image Asynchronously.
Then how can I set images into the image view?
-(void)GenerateImageView{
for (int ivalue = 0; ivalue < 100; ivalue++) {
imageView = [[UIImageView alloc] init];
//Give tag to the image view
imageView.tag = ivalue;
[imageView setBackgroundColor:[UIColor whiteColor]];
CGFloat xOrigin =ivalue *ascrollView.frame.size.width+50;
imageView.frame=CGRectMake(xOrigin40,imgYpos,ascrollView.frame.size.width-20, scrollViewHight);
//set imageview into the scroll view
[ascrollView addSubview:imageView];
}
}
Then how can I set images into the imageview?
UIImageView *imageView = [ascrollView viewWithTag:some_tag];
if ([imageView isKindOfClass:[UIImageView Class]])
imageView.image = your_UIImage_object;
u can not access the directly image view.And also make sure ur tag not start with 0.bcs 0 is a by default main view tag
imageView = (UIImageView *)[ascrollView viewWithTag:some_tag];
imageView.image = your_UIImage_object;
You could use the code Avt suggested, but instead of reinventing the wheel, I would suggest to look into
AFNetworking
an open-source networking lib. It comes with an extension to the UIImageView which allows you to load the images asynchronously out-of-the-box. There are many other useful features too.
After importing the extension you could then use:
[imageView setImageWithURL:[NSURL URLWithString:#"yourImageURL"]];
the image gets loaded asynchronously and automaticly set when it's done loading.
I'm working in Xcode and i have a loop cycle in which i dynamically create UIImageViews and UITextviews and insert them in a UIScrollView. In every row, i create 4 UIImageViews and 2 UITextViews, so the code looks like this:
for (int i=0; i<dim; i++){
UITextView *textView1= [[UITextView alloc] initWithFrame:CGRectMake(0, 0, screenWidth/2, 37)];
UITextView *textView2= [[UITextView alloc] initWithFrame:CGRectMake(screenWidth/2, 0, screenWidth/2, 37)];
UIImageView *imageView1 = [[UIImageView alloc] initWithFrame:CGRectMake(0,50,screenWidth/4,100)];
UIImageView *imageView2 = [[UIImageView alloc] initWithFrame:CGRectMake(screenWidth/4,50,screenWidth/4,100)];
UIImageView *imageView3 = [[UIImageView alloc] initWithFrame:CGRectMake(screenWidth/2,50,screenWidth/4,100)];
UIImageView *imageView4 = [[UIImageView alloc] initWithFrame:CGRectMake(screenWidth*3/4,50,screenWidth/4,100)];
}
The code to set images in UIImageViews, text in UITextViews and show them in the UIScrollView works great and i don't post it because it's too long.
My problem is: when i click on an image, i call methods in which i want to make change to the ImageViews and TextViews of the same row, how can i identify them?
Detecting the image clicked is not a problem using the recognizer.view, to detect other images of the same row i tried to set a tag to the views and then call "viewWithTag" to find them, but i have problems because the elements of the same row have the same tag value and i make confusion.
My target is for example:
When i click on imageView1 in the first row should change image in imageView3 of the same row.
When i click on imageView3 in the fourth row should change text in textView2 of the same row.
And so on..
Is there any alternative method without using the tag attribute?
I hope I explained myself
You can use the tag property, but without using the same tag more then once. Some little math should do the trick to identify views in the same row by their tags...
BUT:
I wouldn't recommend using tags. Make yourself a custom view class, e.g. MyRow, containing the 6 views belonging together as subviews. From there you can go anywhere.
Got a problem, invent an object. Always works.
BIGGER BUT: I'd strongly recommend to go with UICollectionView or UITableView.
UIView has a "tag" property, which you can use for anything you want. The default value is 0 and it doesn't do anything at all, except store the value.
Typically you would set the tag to be an array index.
So you could do:
textView1.tag = i;
textView2.tag = i;
imageView1.tag = i;
imageView2.tag = i;
imageView3.tag = i;
imageView4.tag = i;
Or perhaps something more clever, like:
textView1.tag = 1000000 + i;
textView2.tag = 2000000 + i;
imageView1.tag = 3000000 + i;
imageView2.tag = 4000000 + i;
imageView3.tag = 5000000 + i;
imageView4.tag = 6000000 + i;
Or maybe you could have an array property mapping them:
#property NSMutableArray tagMap;
textView1.tag = self.tagMap.count;
[self.tagMap addObject:#{#"var": #"textView1", #"index":[NSNumber numberWithInteger:i]}];
I am trying to create a couple of UIImageViews (preferably with a for loop) and then afterwards move them, but I don't know how because I'm having trouble figuring out how to reference them if they will be made programmatically.
So I want something like this:
for (int i = 0; i < 2; i++)
{
UIImageView *iv = [[UIImageView alloc]initWithImage:[UIImage imageNamed: picturo]];
CGRect rect = CGRectMake((i * 50) + 50,30, 25, 25);
[iv setFrame:rect];
iv.tag = i;
[self.view addSubview:iv];
}
(iv with tag of 0).center.y = 80; // <-- How do I do that!!
Obviously this example has no practical use and I could just change y value of 'rect' above to 80, but I want to know how to:
a. Create multiple uiimageviews (or any object for that matter) and be able to identify/reference/manipulate each one individually (I don't know how but I would assume by either naming them uniquely or using tags) and
b. Be able to identify/reference/manipulate an object that was created programmatically.
creating views with tags works the way you have it.
To access those views use the viewWithTag property on a view to identify one of it's subviews:
UIView* subview = [self.view viewWithTag:0];
subview.center = CGPointMake(subview.center.x, 80);
(you cannot write to a view.center's x or y, you have to recreate the whole thing. Likewise with other geometric structs such as CGSize, CGRect)