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Views A and B are equal in width (set up via a constraint). The actual width will vary at runtime.
What I want to do is arrange view A such that it is horizontally centered on B but offset to the left by 1/10th of the total width.
In other words, if views A and B were 100 units in length, I'd want A to be positioned 10 units to the left of B. If the width were 150 units then the A position would be 15 to the left, etc.
I thought I could do this with either a leading constraint or a centerX constraint using a multiplier of 0.9, but it isn't working out the way I want.
What's the best solution?
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I can't get my latest iPhone app to run in portrait mode only. In Xcode I've checked only the box that says "Portrait" under Device Orientation, and I've also examined the Info.plist file to ensure that there aren't any hidden settings for other orientations.
I've also tried checking or un-checking iPad, and checking "Requires Full Screen" when that option appears. No matter what I do, when I run the app on my phone and rotate the screen, the interface rotates.
What am I doing wrong?
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I've got an iOS project that I've been working on for some months. Just recently, I started seeing a compiler error to the effect that "Referencing instance requires that X conforms to Equatable". It shows up in places where you'd expect something to be Equatable, such as the argument to firstIndexOf: on an array.
The class in question is written in Swift, but descents from an Objective-C base class. I know there are some issues with how Equatable interacts with Obj-C but I think I've done it right. The base class extends NSObject, and the subclass implements both the isEqual function and the static == function. (I don't think the latter is necessary but I included it just in case).
I've tried explicitly including "Equatable" in the definition of the subclass but the compiler rejects this as "Redundant conformance to protocol". I'm not exactly sure how that works since NSObject doesn't extend Equatable but I guess Swift considers them equivalent.
Here's where things get super weird though. Xcode still builds and runs the project despite the compiler error, and the code runs, and it works. I even put a breakpoint in the isEqual function to make sure it was getting called. Also, when I clean and rebuild the project, the compiler error often disappears for some time, reappearing hours or days later. So I think this must be some kind of bug in Xcode or Swift itself.
What do you think?
Frank
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How do I get a background image to fill the screen in my launch screen on an iPhone X?I have aligned the image to the top and bottom layout guides, but this leaves large white gaps.
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I've got a fairly old app that I first built back in 2014, and have been maintaining over the years.
One of the screens in the app uses the camera to scan barcodes. The barcodes we scan are printed on labels, and are in the org.iso.Code128 format.
When the app was first developed, I simply set the metadataObjectTypes property of AVCaptureMetadataOutput to all available types. This worked fine. The app scanned our barcodes very quickly with almost no issues.
In 2017, we started seeing issues where barcode scanning was becoming slower. I reasoned that having it configured to scan for every possible barcode format might be the issue, so I went in and changed the code to have it scan only for the org.iso.Code128 format. This helped, for a while.
Now, we're seeing the problem again in iOS 14 devices. On some devices it is nearly impossible to scan the barcodes. On others, you have to wait 20 or 30 seconds before the barcode is recognized.
What could be causing this issue?
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Will Apple continue to support it, or will we wake up one day to find that Swift is the only viable language?It's a serious question. Careers depend on it. I don't accept the "No comment" approach that Apple usually takes. It's cruel.I'm willing to put the time into learning Swift if I have to. I'm not going to do it if I don't. I want to know.Frank
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Is there any way to get Xcode to remember my Git credentials?
My company uses a service called Beanstalk to host our Git repositories. Beanstalk is not one of the choices available under "Source Control Accounts", but the repository itself is a standard Git repository.
I can access it by giving my credentials at the time I pull or push, but Xcode forgets them whenever I close it.
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Hi,
I'm working with a BLE device manufacturer on a new device for which I'm tasked with developing the iOS app.
The hardware developer told me: "In response to a Scan request (from a phone or other device) the BLE stack is configured to include a device identifier". The device identifier is something I need to see in the advertising packet before I connect to the device.
I don't know what a "Scan request" is. Is this something I have to specifically ask for in my app? Is it something iOS does automatically?
Thanks,
Frank
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Hi,According to the documentation for the AVVideoCompositing protocol:"When creating instances of custom video compositors, AV Foundation initializes them by calling init and then makes them available as the value of the customVideoCompositor property of the object to which it was assigned. You then can do any additional setup or configuration to the custom compositor."AVMutableVideoComposition has a customVideoCompositorClass property, but does not have a customVideoCompositor property.Am I misunderstanding this? I need to access the instance to set some properties on it, but I cannot.Thanks,Frank
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I've seen examples of Swift code with #if DEBUG / #endif, and have even used it myself.I know exactly how preprocessor macros work in c, c++ and Objective-C. In those languages, I know I can say:#ifdef DEBUG ... some code ...#endifAnd I know that if the DEBUG flag is false at build time, the code will not only not run, but it won't even be compiled. This is important to me because the code inside that block contains some sensitive information that must not end up in my compiled code for non-debug builds.In Swift, I'm really not sure what happens. I know the code doesn't execute, but I'm also told that Swift doesn't have a preprocessor. So, what exactly is going on here?Specifically, can I hide sensitive information inside an #if DEBUG block in Swift and be assured that it won't get compiled or in any way be present in the executable when the DEBUG flag is false? Or is #if DEBUG evaluated at runtime in Swift?Thanks,Frank
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I'm trying to send my app silent push notifications by setting the "content-available" flag to 1 in the notification payload. This works, but there is a problem: if my app is not running in the foreground, the notification is visible on the home screen. I don't want this: I just want the app to see it, without waking up the screen or alerting the user.
If the app is open when the notification comes in, it works as expected; I receive the notification inside my app, and iOS does not display any alert or banner.
I configured my app with the "Remote Notifications" background mode.
What am I doing wrong?
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I have an app that I distribute to an Enterprise customer via private app store distribution. Recently, I published an update. The update went through the App Store review process, was approved, and is currently listed as Ready for Sale.
However, my Enterprise customer says he cannot access the update. His view of the app still shows the latest version as being the prior version.
I can't figure out what is wrong. Is there some additional step I need to take to make sure the app is available to him?
Thanks,
Frank
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Hi,
I'm looking at the function activityViewController(_:dataTypeIdentifierForActivityType:) in the UIActivityItemSource protocol. The documentation says "For items that are provided as data, returns the UTI for the item." The return type of the function is a String.
I don't know what "UTI" means in this context. The data I'm trying to provide is an HTML document (a string containing HTML). I tried returning "text/html", but I don't think this worked.
I'm also unsure whether my "itemForActivityType" function ought to be providing the HTML as a String, or perhaps converting it to Data first.
The end result I'm seeing is that I can share the HTML document via Mail, and it looks fine, but if I try to air drop it, I get an error that says "Extension request contains input items but the extension point does not specify a set of allowed payload classes."
I'd like my app to be able to share the HTML document via Mail or Airdrop. I don't care if it doesn't support sharing to any other services.
Thanks,
Frank
I need to do something that seems simple but I can't figure out the right syntax.
Given a string, I need to search for the first occurrence of a substring (not a character). If found, I need to create a new string by removing the part of the old string that is before the substring.
I can't see how this is done in Swift. There is a "firstIndexOf" function, but it only searches for one character at a time.
I also know that there is a "range(of:)" function, but I can't find its documentation, and I don't know what the return type is, or how I would use it.
Thanks,
Frank
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I'm trying to figure out the right way to format a Decimal number as a currency value in Swift.
For example, if the Decimal contains the value 25.1 I'd want this to print as "$25.10". If it had the value 25, I'd want "$25.00". If it happened to contain a value like 25.4575, I'd want to round it off and display "$25.46".
There are a confusing amount of functions surrounding Decimals and string formatting. I know I can't just use String(format: "%.2f", value) like I can do with floats and doubles.
There appears to be a new FormatStyle property of Decimal, but I can't use that yet because it requires iOS 15.
Thanks,
Frank
flarosa.