Inability to create my UIImageView classes from string - ios

I am creating subclasses of UIImageView class, something like LittleImageView, RedImageView, etc.
These subclasses have this convenience method for the creation of specific images:
+ (UIImageView *)novo {
UIImageView *newImage = [[super alloc] initWithImage:...
// do stuff
return newImage;
}
When I try to create such classes using this new command by string
id newObject = [NSClassFromString(nameOfClass) novo];
I get a crash with "unrecognized selector sent to class". Apparently objective-c is trying to do a [UIImageView novo] instead of doing a [RedImageView novo], for instance.
Any ideas how to solve this?

I can't reproduce your experience exactly, but there are a few changes you should consider: (1) declare the constructor as returning the derived type, (2) declare the local variable as the derived type, (3) used the derived class to alloc (self, not super)...
// in MyImageView.h
+ (instancetype)myImageView:(UIImage *)image;
// in MyImageView.m
+ (instancetype)myImageView:(UIImage *)image {
MyImageView *miv = [[self alloc] initWithImage:image];
// ...
return miv;
}
Now you can use elsewhere without the sketchy use of id in your local variable declaration. It looks like this, and in my test, generates instances of the correct type...
MyImageView *firstTry = [MyImageView myImageView:nil];
MyImageView *secondTry = [NSClassFromString(#"MyImageView") myImageView:nil];
NSLog(#"%#, %#", firstTry, secondTry);

Related

Unable to set UIImage, always returns nil

This is probably a ridiculous question but I just can't figure it out for the life of me. I have a class which subclasses NSObject which has a property called image setup, like this:
#property (strong, nonatomic) UIImage *image;
Somewhere else I initialize the class and attempt to set the image in the class, like this:
UIImage *image = [UIImage imageNamed:#"Test"];
Class *item = [[Class alloc] init];
item.image = image;
But when I try to call item.image it is always nil.
The image called Test is in the project and is used elsewhere so I know it has access to the image, but for some reason it isn't being copied to the instance of my class. I have put NSLog messages and breakpoints directly after setting the image which have shown it to be nil as well as using commands via the debugger which have also shown the image in the class to be nil while the UIImage I create to copy is not nil.
I know I am doing something wrong but I have searched and can't figure out what it is.
Thanks for looking, any help is much appreciated.
edit:
I am trying to access the image from a method inside of the class.
- (void)save {
if (self.image != nil) {
// do some stuff
} else {
NSLog(#"image is nil");
}
}
And it is always coming up nil.
edit 2:
Thanks again everyone. I figured out what the problem was. I was overriding the setters/getters which was causing the issue.
Is it a .png file? Try doing it like this:
UIImage *image = [UIImage imageNamed:#"Test.png"];

NSInvalidArgumentException exception when adding image to imageView iOS

.H files
#property (strong, nonatomic) LAClaimReport *claimReport;
.M file
#interface LACreateReportViewController ()
{
NSArray *_thumbnails;
LAPhotoThumb *_lastSelectedPhoto;
}
_thumbnails = _claimReport.photos.allObjects;
if (_thumbnails.count >0)
{
_photosCaption.textColor = [UIColor colorWithRed:0/255.0 green:46/255.0 blue:91/255.0 alpha:1];
UIImageView *image = [[UIImageView alloc] initWithFrame:CGRectMake(30, 1838, 300, 600)];
NSLog(#"image:%#" , _thumbnails[0]);
[image setImage:(UIImage *) _thumbnails[0]]; // exception here.
}
NSInvalidArgumentException', reason: '-[LAPhoto size]: unrecognized selector sent to instance 0xa76b720'
Photos is a column in the class file of LAClaimReport. What am i missing in regards to size here? pls guide.
_thumbnails doesn't contain UIImage instances, it contains some other type of object. Enough information isn't included to tell what kind of objects it contains however.
size is a method on UIImage that is used by the image view to determine how to display the image, and whatever object is actually in _thumbnails doesn't implement that method.
Your NSLog(#"image:%#" , _thumbnails[0]); should list the class type that you're trying to use as an image.
make sure that you have UIImage class objects in _thumbnails Array, I Think you have LAPhoto type objects in that array
id arrContent=_thumbnails[0];
if ([arrContent isKindOfClass:[LAPhoto Class]])
{
//read LAPhoto class and find a way to get the UIImage from LAPhoto Object
}
else if ([arrContent isKindOfClass:[UIImage class]])
{
[image setImage:(UIImage *) _thumbnails[0]];
}

accessing a property of an instantiated object with my custom init method

Here's my class with my custom init method:
// Piece.h
#import <Foundation/Foundation.h>
#interface Piece : CCSprite
#property (nonatomic) int pieceNumber;
+(Piece *)initWithPieceImage:(UIImage*)piece pieceName:(int)pName;
#end
// Piece.m
#import "Piece.h"
#implementation Piece
#synthesize pieceNumber = _pieceNumber;
+(id)initWithPieceImage:(UIImage *)piece pieceName:(int)pName
{
return [[[self alloc] initWithPieceImage:piece pieceName:pName] autorelease];
}
-(Piece*)initWithPieceImage:(UIImage *)piece pieceName:(int)pName
{
CCSprite *bgImage = nil;
if ( (self=[super init]) )
{
bgImage = [CCSprite spriteWithCGImage:piece.CGImage
key: [NSString stringWithFormat:#"%i",pName]];
}
return (Piece*)bgImage;
}
#end
I instantiated the Piece class like this to add it to the layer:
Piece *newPiece = [Piece initWithPieceImage:myUIImage pieceName:1];
[newPiece setPieceNumber:2]; //Error in this line
[self addChild: newPiece z:1];
However I have tried it like this and it perfectly works:
Piece *newPiece = [[Piece alloc] init];
[newPiece setPieceNumber:2];
but this is not what I want.
and here is the error I get:
[CCSprite setPieceNumber:]: unrecognized selector sent to instance 0x85f1050
Terminating app due to uncaught exception NSInvalidArgumentException, reason: -[CCSprite setPieceNumber:]: unrecognized selector sent to instance 0x85f1050
Aparently it looks like the problem is how Im trying to init my object.
I'm a newcomer to objective-c so I cant figure out what is wrong here.
any idea of what am I doing wrong here?
How can I achieve this approach and access the properties of my instantiated object with custom init method?
You have a mess in your code. In -(Piece*)initWithPieceImage:(UIImage *)piece pieceName:(int)pName you return a CCSprite object instead of a Piece. You assign self with an object but return another, of an incorrect type.
init returns the correct type (because you haven't reimplemented it), so it works, but you haven't actually initialized the image correctly.
You need to change your method like so:
-(Piece*)initWithPieceImage:(UIImage *)piece pieceName:(int)pName
{
return [super initWithCGImage:piece.CGImage key:[NSString stringWithFormat:#"%i",pName]];
}
It is because in your init method, you are for some reason creating a CCSprite object and returning that instead of the Piece object. Because of that, it will not be an object of your Piece class and will not respond to any of Piece's methods.
Instead of creating a new CCSprite object to set those properties to, you want to set those on self or super.

How to get a UIImage's image as an NSString?

I need to get the value of a UIImage's image as a string.
Previously I was doing:
if(images[imageNo].image == [UIImage imageNamed:#"image1.png"])
{
But now I have a lot more conditions so I would like to use a switch, doing:
switch(images[imageNo].image)
{
case #"image1.png":
break;
}
Is there a way to achieve this? Thanks!
Mmm I am not sure what you want to accomplish here but using [UIImage imageNamed:#"image1.png"], is definitely a very bad way to do the comparison as you are creating a new UIImage object on the fly for no reason at all, furthermore you are using the == operator when you should be using isEqual since they are objects.
I believe what you want to do is convert it to a base 64 string perhaps?. If so you an use this:
NSData *imageData = UIImageJPEGRepresentation(myImage, 1.0);
NSString *encodedString = [imageData base64Encoding];
The answer provided by H2C03 is appropriate. Use a dictionary to associate the names.
However, an alternative is using associative objects. Note that there is a cost in both space and time using associative objects, but they are convenient for just this type of case (adding a category-property).
#interface UIImage (MyImageLabel)
#property (nonatomic, copy) NSString *label;
#end
#import <objc/runtime.h>
#implementation UIImage (MyImageLabel)
static char const kImageLabelKey[1];
- (NSString*)label {
return objc_getAssociatedObject(self, kImageLabelKey);
}
- (void)setLabel:(NSString *)label {
objc_setAssociatedObject(self, kImageLabelKey, label, OBJC_ASSOCIATION_COPY_NONATOMIC);
}
#end
Now, you can have a label property on your UIImage instances, like so:
myImage.label = someLabelStringCouldEvenBeFilename;
and
if ([myImage.label isEqualToString:someString]) {
}
The typical caveats apply regarding anything in a category. Most will encourage you to use a unique prefix or postfix to differentiate your category methods from potential future Apple names.
Note, that you could add another method to the category, like this...
+ (UIImage)myImageNamed:(NSString*)name {
id result = [self imageNamed:name];
[result setLabel:name];
return result;
}
and now you automatically set the label.
Of course, you could do this as a subclass, if you will always be creating your own image, and avoid the "nastiness" associated with associative objects (though all your images need to be MyUIImages).
#interface MyUIImage : UIImage
#property (nonatomic, copy) NSString *label;
#end
#implementation MyUIImage
// Now, you override imageNamed:
+ (UIImage*)imageNamed:(NSString*)name {
UIImage *image = [super imageNamed:name];
self.label = name;
return image;
}
#end
Both of your approaches are incorrect. The first one relies on caching (which is not documented), meanwhile the second is a syntax error - the 'case' keywords expect a compile-time constant expression.
As far as I know, there's no such a method in the iOS SDK that would return an image's filename - simply because it's not a property of the image (what would it return for a programmatically created image?). You should instead try to operate on an NSDictionary, storing the UIImage objects associated with the filenames as keys, and comparing the keys using isEqualToString:.
So you should create your images only once, and store them in a dictionary:
// assuming `images` is an already created instance variable of your class
[images setObject:[UIImage imageNamed:#"ImgOne.png"] forKey:#"ImgOne.png"];
// and so on, with every image you need
// then once you have to check against a file name, use:
UIImage *img = [images objectForKey:#"FileName.png"];
if ([someImage isEqual:img]) {
// you can now be sure that the image set to the object was once named "FileName"
}

UIImageView - How to get the file name of the image assigned?

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];
you can use setAccessibilityIdentifier method for any subclass of UIView
UIImageView *image ;
[image setAccessibilityIdentifier:#"file name"] ;
NSString *file_name = [image accessibilityIdentifier] ;
Nope. You can't do that.
The reason is that a UIImageView instance does not store an image file. It stores a displays a UIImage instance. When you make an image from a file, you do something like this:
UIImage *picture = [UIImage imageNamed:#"myFile.png"];
Once this is done, there is no longer any reference to the filename. The UIImage instance contains the data, regardless of where it got it. Thus, the UIImageView couldn't possibly know the filename.
Also, even if you could, you would never get filename info from a view. That breaks MVC.
No no no… in general these things are possible. It'll just make you feel like a dirty person. If you absolutely must, do this:
Create a category with your own implementation of +imageNamed:(NSString*)imageName that calls through to the existing implementation and uses the technique identified here (How do I use objc_setAssociatedObject/objc_getAssociatedObject inside an object?) to permanently associate imageName with the UIImage object that is returned.
Use Method Swizzling to swap the provided implementation of imageNamed: for your implementation in the method lookup table of the Objective-C runtime.
Access the name you associated with the UIImage instance (using objc_getAssociatedObject) anytime you want it.
I can verify that this works, with the caveat that you can't get the names of UIImage's loaded in NIBs. It appears that images loaded from NIBs are not created through any standard function calls, so it's really a mystery to me.
I'm leaving the implementation up to you. Copy-pasting code that screws with the Objective-C runtime is a very bad idea, so think carefully about your project's needs and implement this only if you must.
There is no native way to do this; however, you could easily create this behavior yourself.
You can subclass UIImageView and add a new instance variable:
NSString* imageFileName;
Then you could override setImage, first setting imageFileName to the filename of the image you're setting, and then calling [super setImage:imageFileName]. Something like this:
-(void) setImage:(NSString*)fileName
{
imageFileName = fileName;
[super setImage:fileName];
}
Just because it can't be done natively doesn't mean it isn't possible :)
if ([imageForCheckMark.image isEqual:[UIImage imageNamed:#"crossCheckMark.png"]]||[imageForCheckMark.image isEqual:[UIImage imageNamed:#"checkMark.png"]])
{
}
Nope. No way to do that natively.
You're going to have to subclass UIImageView, and add an imageFileName property (which you set when you set the image).
Neither UIImageView not UIImage holds on to the filename of the image loaded.
You can either
1: (as suggested by Kenny Winker above) subclass UIImageView to have a fileName property or
2: name the image files with numbers (image1.jpg, image2.jpg etc) and tag those images with the corresponding number (tag=1 for image1.jpg, tag=2 for image2.jpg etc) or
3: Have a class level variable (eg. NSString *currentFileName) which updates whenever you update the UIImageView's image
Or you can use the restoration identifier, like this:
let myImageView = UIImageView()
myImageView.image = UIImage(named: "anyImage")
myImageView.restorationIdentifier = "anyImage" // Same name as image's name!
// Later, in UI Tests:
print(myImageView.restorationIdentifier!) // Prints "anyImage"
Basically in this solution you're using the restoration identifier to hold the image's name, so you can use it later anywhere. If you update the image, you must also update the restoration identifier, like this:
myImageView.restorationIdentifier = "newImageName"
I hope that helps you, good luck!
This code will help you out:-
- (NSString *)getFileName:(UIImageView *)imgView{
NSString *imgName = [imgView image].accessibilityIdentifier;
NSLog(#"%#",imgName);
return imgName;
}
Use this as:-
NSString *currentImageName = [self getFileName:MyIImageView];
In short:
uiImageView.image?.imageAsset?.value(forKey: "assetName")
UIImage has an imageAsset property (since iOS 8.0) that references the UIImageAsset it was created from (if any).
UIImageAsset has an assetName property that has the information you want. Unfortunately it is not public, hence the need to use value(forKey: "assetName"). Use at your own risk, as it's officially out of bounds for the App Store.
Yes you can compare with the help of data like below code
UITableViewCell *cell = (UITableViewCell*)[self.view viewWithTag:indexPath.row + 100];
UIImage *secondImage = [UIImage imageNamed:#"boxhover.png"];
NSData *imgData1 = UIImagePNGRepresentation(cell.imageView.image);
NSData *imgData2 = UIImagePNGRepresentation(secondImage);
BOOL isCompare = [imgData1 isEqual:imgData2];
if(isCompare)
{
//contain same image
cell.imageView.image = [UIImage imageNamed:#"box.png"];
}
else
{
//does not contain same image
cell.imageView.image = secondImage;
}
You can use objective c Runtime feature for associating imagename with the UImageView.
First import #import <objc/runtime.h> in your class
then implement your code as below :
NSString *filename = #"exampleImage";
UIImage *image = [UIImage imagedName:filename];
objc_setAssociatedObject(image, "imageFilename", filename, OBJC_ASSOCIATION_COPY);
UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
//You can then get the image later:
NSString *filename = objc_getAssociatedObject(imageView, "imageFilename");
Hope it helps you.
Get image name Swift 4.2
There is a way if you want to compare button image names that you have in assets.
#IBOutlet weak var extraShotCheckbox: UIButton!
#IBAction func extraShotCheckBoxAction(_ sender: Any) {
extraShotCheckbox.setImage(changeCheckBoxImage(button: extraShotCheckbox), for: .normal)
}
func changeCheckBoxImage(button: UIButton) -> UIImage {
if let imageView = button.imageView, let image = imageView.image {
if image == UIImage(named: "checkboxGrayOn") {
return UIImage(named: "checkbox")!
} else {
return UIImage(named: "checkboxGrayOn")!
}
}
return UIImage()
}
Swift 3
First set the accessibilityIdentifier as imageName
myImageView.image?.accessibilityIdentifier = "add-image"
Then Use the following code.
extension UIImageView {
func getFileName() -> String? {
// First set accessibilityIdentifier of image before calling.
let imgName = self.image?.accessibilityIdentifier
return imgName
}
}
Finally, The calling way of method to identify
myImageView.getFileName()
I have deal with this problem, I have been solved it by MVC design pattern, I created Card class:
#interface Card : NSObject
#property (strong,nonatomic) UIImage* img;
#property (strong,nonatomic) NSString* url;
#end
//then in the UIViewController in the DidLoad Method to Do :
// init Cards
Card* card10= [[Card alloc]init];
card10.url=#"image.jpg";
card10.img = [UIImage imageNamed:[card10 url]];
// for Example
UIImageView * myImageView = [[UIImageView alloc]initWithImage:card10.img];
[self.view addSubview:myImageView];
//may you want to check the image name , so you can do this:
//for example
NSString * str = #"image.jpg";
if([str isEqualToString: [card10 url]]){
// your code here
}
use below
UIImageView *imageView = ((UIImageView *)(barButtonItem.customView.subviews.lastObject));
file_name = imageView.accessibilityLabel;
The code is work in swift3 - write code inside didFinishPickingMediaWithInfo delegate method:
if let referenceUrl = info[UIImagePickerControllerReferenceURL] as? NSURL {
ALAssetsLibrary().asset(for: referenceUrl as URL!, resultBlock: { asset in
let fileName = asset?.defaultRepresentation().filename()
print(fileName!)
//do whatever with your file name
}, failureBlock: nil)
}

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