I have a UIImageView whose user interaction is true and to which I have given a tap gesture recognizer, whose action handler is as follows:
#IBAction func tap(_ sender:UITapGestureRecognizer) {
let iv = sender.view as! UIImageView
let im = iv.image!
let im2 = UIGraphicsImageRenderer(size:im.size).image { _ in
UIColor.red.setFill()
UIBezierPath(rect: CGRect(origin:.zero, size:im.size)).fill()
}
iv.image = im2
}
I expect the image displayed, when I tap the image view, to be replaced by a solid red image. This works fine on my High Sierra machine running Xcode 9.4. But on my Sierra MacBook running Xcode 9.2, nothing visibly happens.
It's weird. By pausing in the debugger, I can see that the new image is being constructed correctly:
The image is being replaced, but the image view isn't being redrawn. Adding calls like setNeedsDisplay does nothing.
Moreover, if I then proceed to replace the image view's image with a different image, I see the red image!
iv.image = im2
delay(0.5) {
iv.image = im // causes im2 to appear!
}
Some sort of behind-the-scenes caching is evidently causing the image view to get behind in its display by one image.
Can anyone shed light on this? It's presumably a bug in iOS itself, and perhaps in 9.2 specifically; how would one work around it? (Obviously one could substitute another image view wholesale, but that wouldn't tell us what's going on with the caching.)
This seems to be a workaround:
iv.image = im2
delay(0.05) {
iv.image = nil
iv.image = im2
}
But what a horror... Omitting any of those assignments, or reducing the delay to zero (e.g. by calling DispatchQueue.main.async instead), causes the workaround to fail.
Encountered this problem in Xcode 13. Set the contentModel to center in the xib file
or
iv.contentMode = .center
Related
I was wondering what I would need if I wanted to use a mask image to get my UIImageView in a specific shape. From what I understand, to create a mask, I need to have an image with the shape of the mask all black on top of a white background. Something like this, for example:
First of all, is this sufficient to shape an image view, and if so, how do I do it in Swift 3? I can only find masking code that is either outdated or written in Objective-C. I've tried simply assigning the image above to an UIImageView and then assign the image view to the mask property of the UIImageView I want to shape, like so:
self.defaultImageView.mask = self.maskImageView
This didn't do anything. It just made self.maskImageView disappear (both image view's added through the storyboard and connected using IBOutlet properties). I'm sure I'm forgetting to do something. It can't be this simple. I would appreciate it if someone could help me out. Like I said, I put both image views on the exact same spot, on top of each other, in the storyboard.
UPDATE:
My first attempt to set the mask programmatically after deleting it from my storyboard.
let layer:CALayer = CALayer()
let mask:UIImage = UIImage(named: "Black-Star-Photographic-Agency")!
layer.contents = mask
layer.frame = CGRect(x: 0, y: 0, width: ((self.defaultImageView.image?.size.width)!), height: (self.defaultImageView.image?.size.height)!)
self.defaultImageView.layer.mask = layer
self.defaultImageView.layer.masksToBounds = true
The result was that the image view had completely disappeared and wasn't visible anymore. Am I doing something, am I forgetting something or both?
You should use a png image, which supports transparency, unlike jpg.
In Photoshop your image should look similar to this:
It doesn't matter if your shape is black or white. What matters is transparency of each pixel. Opaque area (black in this case) will be visible and transparent area will get trimmed.
Edit:
You should not create mask view from storyboard if you do so. It is not going to be a part of your view hierarchy. Just add it programmatically like this:
let maskView = UIImageView()
override func viewDidLoad() {
super.viewDidLoad()
maskView.image = UIImage(named: "mask")
imageView.mask = maskView
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
maskView.frame = imageView.bounds
}
Output:
Here is a test project to show how it's working.
Also if you're using a custom frame/image and run into the mask not showing properly, try setting the content mode of the mask:
maskView.contentMode = .scaleAspectFit
For some reason I am unable to add a UIImageView to my app. This is the code I am using and I have searched for quite a while to figure this out but haven't had any luck.
super.viewDidLoad()
let cloudimage = UIImage(named: "cloud")
let cloudView = UIImageView(image: cloudimage)
self.view.addSubview(cloudView)
cloudView.frame = CGRectMake(0,0,100,200)
The image is a .png in my assets folder so I don't think it's that. I do have auto layout settings enabled if that is an issue? I know it can be an issue with moving a UIImageView around by using its frame, but I think I should still be able to place the image in the View no problem with this code.
I am not quite sure what to do any suggestions would be great, this is extremely frustrating.
If your image is nil, your UIImageView will not render anything. Try debug your view hierarchy.
https://developer.apple.com/library/tvos/documentation/DeveloperTools/Conceptual/debugging_with_xcode/chapters/special_debugging_workflows.html
http://www.raywenderlich.com/98356/view-debugging-in-xcode-6
you need to add UIimageview to main view.
self.view.addSubview(cloudView)
Try by giving the image extension also while setting to UIImage
let cloudimage = UIImage(named: "cloud.png")
let cloudView = UIImageView(image: cloudimage)
cloudView.frame = CGRectMake(0,0,100,200)
self.view.addSubview(cloudView)
Checked and its working.
When customizing (by subclassing) PFLogInViewController; I have a problem with the logo. I use a square picture which for some reason gets distorted, in fact flattened.
Here is the code:
UIImage *logoImage;
logoImage = [UIImage imageNamed:#"myLogo.png"]; // 152 x 152 pixels.
self.logInView.logo = [[UIImageView alloc] initWithImage:logoImage];
self.logInView.logo.layer.cornerRadius = 7.0;
self.logInView.logo.clipsToBounds = YES;
Am I doing something wrong? Or is the issue in a different place?
I ran into the same problem, and after viewing Dare's answer, I came up with a solution.
Override viewDidLoad:
override func viewDidLoad() {
super.viewDidLoad()
let logo = UIImageView(image: UIImage(named: "logo"))
logo.contentMode = .ScaleAspectFill
logInView!.logo = logo
}
This solved my scaling issue. However, depending on the size of your logo, it may possibly bleed out of the screen. A dirty workaround is overriding viewDidLayoutSubviews and hardcoding the logo object's origin:
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
logInView!.logo!.frame.origin.y += 200 //here I moved the logo down by 200 points
}
Setting the image property does not change the size of a UIImageView. Call sizeToFit to adjust the size of the view to match the image. You could also set its frame explicitly to 152x152 with self.logInView.logo.frame = CGRectMake(0,0,152,152); or something similar. The other thing to check out is the image view's content mode. Maybe UIViewContentModeCenter or UIViewContentModeScaleAspectFit.
so what I currently wish to accomplish is for an image to be printed on the background of the IOS simulator screen, so inside of my viewDidLoad, I have this
var img = UIImage(named: "paper.jpg")
This can create the image variable, but I haven't found how to display it on the screen yet. It may seem like a trivial problem, but I haven't found any documentation on this online after searching for awhile. Thanks for reading.
Refer to the UIColor documentation.
In Swift, you have to call a convenience initializer. This is because in Swift, all Objective-C class methods which return an instance of their class become convenience initializers.
Here's how it looks in Swift:
self.view.backgroundColor = UIColor(patternImage: UIImage(named: "paper.jpg"))
+ (UIColor *)colorWithPatternImage:(UIImage *)image returns a UIColor instance, so it will become a convenience initializer in Swift. Similarly, UIImage imageNamed: becomes init(patternImage image: UIImage!).
since this is the marked answer, I felt the need to add a bit more code for completion.
as #senior has posted in his answer another way to add an image to your background is by the use of adding a UIImageView as a subview like so:
let img = UIImage(named: "paper.jpg")
let imgView = UIImageView(image: img)
self.view.addSubview(imgView)
You have to add your image to an ImageView and add this to the current view as a subview,
let img = UIImage(named: "paper.jpg")
let imgView = UIImageView(image: img)
self.view.addSubview(imgView)
iOS automatically flips the entire ViewController when using a RTL language like Arabic and does a great job with most of the layout, especially text. The default behavior is to flip the layout but leave UIImageViews the same orientation (since you generally don't want to reverse images).
Is there a way to specify that some images should be flipped (such as arrows) when the phone is set to a RTL language?
iOS 9 includes the imageFlippedForRightToLeftLayoutDirection method that you can use, that automatically flips the image in a UIImageView when in an RTL localization.
The best solution I found to date is marking the image in the assets file as mirror.
We can use imageFlippedForRightToLeftLayoutDirection which returns flipped image if current language is RTL(right to left). i.e
Objective-c
UIImage * flippedImage = [[UIImage imageNamed:#"imageName"] imageFlippedForRightToLeftLayoutDirection];
Swift 3
let flippedImage = UIImage(named: "imageName")?.imageFlippedForRightToLeftLayoutDirection()
Source: Apple Docs
You have to manually flip the UIImages in the UIImageViews you want when the phone is set to a RTL language. This can be easily achieved with this code:
UIImage* defaultImage = [UIImage imageNamed:#"default.png"];
UIImage* flipImage = [UIImage imageWithCGImage:sourceImage.CGImage scale:1.0 orientation: UIImageOrientationUpMirrored];
myImageview.image = flipImage;
I ended up using localized images for the forward and back arrows. This had the advantage of not having to add code each place the image was used and gives the opportunity to clean up the arrows if there are gradients that don't work well flipped.
While we wait for iOS 9 improved right to left support you could create a UIImageView subclass and override setImage to mirror inside the images as #nikos-m suggests and calling super.image = flipImage.
That way you can easily set all the images views you want to flip using custom classes in Interface Builder instead of having to add IBOutlets.
Swift 5
If you want to individualize the image flip, you can register each image with the direction you want since the layout direction is a trait:
let leftToRight = UITraitCollection(layoutDirection: .leftToRight)
let rightToLeft = UITraitCollection(layoutDirection: .rightToLeft)
let imageAsset = UIImageAsset()
let leftToRightImage = UIImage(named: "leftToRightImage")!
let rightToLeftImage = UIImage(named: "rightToLeftImage")!
imageAsset.register(leftToRightImage, with: leftToRight)
imageAsset.register(rightToLeftImage, with: rightToLeft)
This is the same as configuring it in the asset catalogue as #SergioM answered.