uiimage interview questions
Top uiimage frequently asked interview questions
Is it possible to read the name of an UIImageView's UIImage
that's presently stored in the UIImageView?
I was hoping you could do something kind of like this, but haven't figured it out.
NSString *currentImageName = [MyIImageView getFileName];
Source: (StackOverflow)
I am trying to load UIImage object from NSData, and the sample code was to NSImage, I guess they should be the same. But just now loading the image, I am wondering what's the best to troubleshoot the UIImage loading NSData issue.
Source: (StackOverflow)
If I have a UIImage from an imagePicker, how can I save it to a subfolder in the documents directory?
Source: (StackOverflow)
There are a lot of resources about how to display a PDF in an App's UIView. What I am working on now is to create a PDF from UIViews.
For example, I have a UIView, with subviews like Textviews, UILabels, UIImages, so how can I convert a big UIView as a whole including all its subviews and subsubviews to a PDF?
I have checked Apple's iOS reference. However, it only talks about writing pieces of text/image to a PDF file.
The problem I am facing is that the content I want to write to a file as PDF is a lot. If I write them to the PDF piece by piece, it is going to be huge work to do.
That's why I am looking for a way to write UIViews to PDFs or even bitmaps.
I have tried the source code I copied from other Q/A within Stack Overflow. But it only gives me a blank PDF with the UIView bounds size.
-(void)createPDFfromUIView:(UIView*)aView saveToDocumentsWithFileName:(NSString*)aFilename
{
// Creates a mutable data object for updating with binary data, like a byte array
NSMutableData *pdfData = [NSMutableData data];
// Points the pdf converter to the mutable data object and to the UIView to be converted
UIGraphicsBeginPDFContextToData(pdfData, aView.bounds, nil);
UIGraphicsBeginPDFPage();
// draws rect to the view and thus this is captured by UIGraphicsBeginPDFContextToData
[aView drawRect:aView.bounds];
// remove PDF rendering context
UIGraphicsEndPDFContext();
// Retrieves the document directories from the iOS device
NSArray* documentDirectories = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES);
NSString* documentDirectory = [documentDirectories objectAtIndex:0];
NSString* documentDirectoryFilename = [documentDirectory stringByAppendingPathComponent:aFilename];
// instructs the mutable data object to write its context to a file on disk
[pdfData writeToFile:documentDirectoryFilename atomically:YES];
NSLog(@"documentDirectoryFileName: %@",documentDirectoryFilename);
}
Please help. Thanks.
Source: (StackOverflow)
I know it's possible to tint a rectangular image by drawing a CGContextFillRect over it and setting the blend mode. However, I can't figure out how to do a tint on a transparent image such as an icon. It must be possible since the SDK does it itself on tab-bars in such. Would anyone be able to provide a snippet?
UPDATE:
Lots of great suggestions have been given for this problem since I originally asked. Be sure to read through all the answers to figure out what suits you best.
UPDATE (Apr 30, 2015):
With iOS 7.0, I can now just do the following, which would satisfy the needs of my original question. But if you have more complicated cases, check out all the answers.
UIImage *iconImage = [[UIImage imageNamed:@"myImageName"] imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
UIImageView *icon = [[UIImageView alloc] initWithImage:iconImage];
icon.tintColor = [UIColor redColor];
Source: (StackOverflow)
I am trying to mask an image something like this:
I found this tutorial but it did not mention where I can find Image.png or mask.png!
TUTORIAL
Would you please help me?
EDIT:
- (void) viewDidLoad {
UIImage *OrigImage = [UIImage imageNamed:@"dogs.png"];
UIImage *mask = [UIImage imageNamed:@"mask.png"];
UIImage *maskedImage = [self maskImage:OrigImage withMask:mask];
myUIIMage.image = maskedImage;
}
Source: (StackOverflow)
I am using the following code for an image picker. But when I run it in the simulator, I have a memory leak and I get a warning about presentModalViewcontroller:animated being deprecated in iOS6. I also get dismissModalViewController:animated deprecated. I'm using the SDK 6.1.
Code for ImagePicker:
- (void)showAlbum:(id)sender {
imagePicker=[[UIImagePickerController alloc]init];
imagePicker.delegate = self;
imagePicker.allowsEditing =NO;
imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
[self presentModalViewController:imagePicker animated:YES];
}
- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{
//release picker
[picker dismissModalViewControllerAnimated:YES];
}
Source: (StackOverflow)
I'm currently uploading an image to a server using Imgur on iOS with the following code:
NSData* imageData = UIImagePNGRepresentation(image);
NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString* fullPathToFile = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"SBTempImage.png"];
[imageData writeToFile:fullPathToFile atomically:NO];
[uploadRequest setFile:fullPathToFile forKey:@"image"];
The code works fine when run in the simulator and uploading a file from the simulator's photo library because I'm on a fast ethernet connection. However, the same code times out on the iPhone when selecting an image taken with the iPhone. So, I tried it by saving a small image from the web and attempting to upload that, which worked.
This leads me to believe the large images taken by the iPhone are timing out over the somewhat slow 3G network. Is there any way to compress/resize the image from the iPhone before sending it?
Thanks!
Source: (StackOverflow)
I'd like to load an image from a URL in my application, so I first tried with Objective-C and it worked, however, with Swift, I've a compilation error:
'imageWithData' is unavailable: use object construction 'UIImage(data:)'
My function:
@IBOutlet var imageView : UIImageView
override func viewDidLoad() {
super.viewDidLoad()
var url:NSURL = NSURL.URLWithString("http://myURL/ios8.png")
var data:NSData = NSData.dataWithContentsOfURL(url, options: nil, error: nil)
imageView.image = UIImage.imageWithData(data)// Error here
}
In Objective-C:
- (void)viewDidLoad {
[super viewDidLoad];
NSURL *url = [NSURL URLWithString:(@"http://myURL/ios8.png")];
NSData *data = [NSData dataWithContentsOfURL:url];
_imageView.image = [UIImage imageWithData: data];
_labelURL.text = @"http://www.quentinroussat.fr/assets/img/iOS%20icon's%20Style/ios8.png";
}
Can someone please explain me why the imageWithData: doesn't work with Swift, and how can I solve the problem.
Source: (StackOverflow)
This question already has an answer here:
I'm creating a colored image like this:
CGRect rect = CGRectMake(0, 0, 1, 1);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context,
[[UIColor redColor] CGColor]);
// [[UIColor colorWithRed:222./255 green:227./255 blue: 229./255 alpha:1] CGColor]) ;
CGContextFillRect(context, rect);
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
and then use it as the background image of a button:
[resultButton setBackgroundImage:img forState:UIControlStateNormal];
This works great using the redColor, however I want to use an RGB color (as shown in the commented line). When I use the RGB color, the buttons background isn't changed.
What am I missing?
Source: (StackOverflow)
I have a URL for an image (got it from UIImagePickerController) but I no longer have the image in memory (the URL was saved from a previous run of the app). Can I reload the UIImage from the URL again?
I see that UIImage has a imageWithContentsOfFile: but I have a URL. Can I use NSData's dataWithContentsOfURL: to read the URL?
EDIT1
based on @Daniel's answer I tried the following code but it doesn't work...
NSLog(@"%s %@", __PRETTY_FUNCTION__, photoURL);
if (photoURL) {
NSURL* aURL = [NSURL URLWithString:photoURL];
NSData* data = [[NSData alloc] initWithContentsOfURL:aURL];
self.photoImage = [UIImage imageWithData:data];
[data release];
}
When I ran it the console shows:
-[PhotoBox willMoveToWindow:] file://localhost/Users/gary/Library/Application%20Support/iPhone%20Simulator/3.2/Media/DCIM/100APPLE/IMG_0004.JPG
*** -[NSURL length]: unrecognized selector sent to instance 0x536fbe0
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSURL length]: unrecognized selector sent to instance 0x536fbe0'
Looking at the call stack, I'm calling URLWithString, which calls URLWithString:relativeToURL:, then initWithString:relativeToURL:, then _CFStringIsLegalURLString, then CFStringGetLength, then forwarding_prep_0, then forwarding, then -[NSObject doesNotRecognizeSelector].
Any ideas why my NSString (photoURL's address is 0x536fbe0) doesn't respond to length? Why does it say it doesn't respond to -[NSURL length]? Doesn't it know that param is an NSString, not a NSURL?
EDIT2
OK, the only problem with the code is the string to URL conversion. If I hardcode the string, everything else works fine. So something is wrong with my NSString and if I can't figure it out, I guess that should go in as a different question. With this line inserted (I pasted the path from the console log above), it works fine:
photoURL = @"file://localhost/Users/gary/Library/Application%20Support/iPhone%20Simulator/3.2/Media/DCIM/100APPLE/IMG_0004.JPG";
Source: (StackOverflow)
I would like to create a 1x1 UIImage dynamically based on a UIColor.
I suspect this can quickly be done with Quartz2d, and I'm poring over the documentation trying to get a grasp of the fundamentals. However, it looks like there are a lot of potential pitfalls: not identifying the numbers of bits and bytes per things correctly, not specifying the right flags, not releasing unused data, etc.
How can this be safely done with Quartz 2d (or another simpler way)?
Source: (StackOverflow)
On iOS 6 SDK I wrote the following lines of code to display an image inside a button:
NSURL *thumbURL2 = [NSURL URLWithString:@"http://example.com/thumbs/2.jpg"];
NSData *thumbData2 = [NSData dataWithContentsOfURL:thumbURL2];
UIImage *thumb2 = [UIImage imageWithData:thumbData2];
[btn2 setImage:thumb2 forState:UIControlStateNormal];
[self.view addSubview:btn2];
But now with Xcode 5 and iOS 7 this doesn't work. The button doesn't contain the image. The button is filled with blue color.
Source: (StackOverflow)