I just migrated my project from Swift 2.2 to Swift 3.0 with Xcode 8 beta.
I have something similar to the following code (you can paste this into a playground):
import Foundation
let datesWithCount: [(Date, Int)] = [(Date(), 1), (Date(), 2), (Date(), 3)]
let dates: [Date] = datesWithCount.sorted {
$0.0 < $1.0
}.prefix(1).map {
return $0.0
}
In Swift 2.2 this compiled fine. However, with Swift 3.0 I get the error
Ambiguous use of 'prefix'
The only way to get this to compile in Swift 3.0 is to split out the map into a separate line:
let sortedDatesWithCount = datesWithCount.sorted {
$0.0 < $1.0
}.prefix(1)
let mappedDates = sortedDatesWithCount.map {
return $0.0
}
BTW, in the actual code I'm returning NSNotification objects from the map not Dates but the error is the same. I just used Date here for making the example simple.
Is there any way to get this to compile as a one liner?
UPDATE: Created a JIRA for the Swift project.
It works if you make the ArraySlice into an Array before passing it to map:
let dates: [Date] = Array(datesWithCount.sorted {
$0.0 < $1.0
}.prefix(1)).map { return $0.0 }
This looks like a type inference bug in the compiler.
Related
I have following problem:
I have iOS application with C++ core. Data is bridged through C++<->ObjCpp<->ObjC chain, data structures are later imported in swift from ObjC.
I have optional<vector<optional>> in one of my structures and there is problem with importing it. Vector is converted to NSList, which is populated by data. Because there can't be nil in NSList, I add NSNull to it. If vector isn't optional - I can work with it in Swift, though it isn't very convenient.
let arr = struct.myArray as NSArray
var swift_arr: [UUID?] = []
for val in arr {
if val is NSNull {
swift_arr.append( nil )
} else if val is NSUUID {
swift_arr.append( val as? UUID )
} else {
fatalError()
}
}
But if array is optional - there is big problem, because when I try to bind optional value, Swift tries to convert it to [UUID?] from NSArray, and when there is NSNull among NSUUIDs, it crashes, because NSNull cannot be converted to UUID.
Is there any proper way to handle such arrays?
I'm trying to format an integer to display it as minutes, but I can't get the syntax right and the docs are still light on this. This is what I'm trying:
let value: Int = 20
Text(value.formatted(.components(style: .abbreviated, fields: [.minute])))
// Compile error: Instance method 'formatted' requires the types 'Int' and 'Date.ComponentsFormatStyle.FormatInput' (aka 'Range<Date>') be equivalent
I'm trying to display: 20 min. How can this be done using the new Foundation formatters improvements from WWDC 2021?
I can do this the old way like this:
static let formatter: DateComponentsFormatter = {
let formatter = DateComponentsFormatter()
formatter.unitsStyle = .short
formatter.allowedUnits = [.minute]
return formatter
}()
Self.formatter.string(for: DateComponents(minute: value))
to format an integer you need a NumberFormatter. Or you could just do:
Text("\(value) min")
I'm having a problem with a Swift 2 to 3 conversion piece of work and some of the remains syntax giving: Value of type '[Any]' has no member errors.
I was hoping someone could point me at a good solution.
Swift 2 code
Swift 2 code
func search() {
epsonPrinters = [Printer]()
starPrinters = [Printer]()
epson_startSearching()
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) { [unowned self] in
let devices = SMPort.searchPrinter()
self.starPrinters = devices.map { portInfo -> Printer in
let p = Printer(
id: portInfo.modelName,
make: "Star Micronics",
model: portInfo.modelName,
portName: portInfo.portName)
if let name = portInfo.modelName as? String {
p.emulation = name.containsString("TSP143") ? "StarGraphics" : "StarLine"
}
return p
}
}
}
Swift 3 Code (I've added comments above areas with errors)
func search() {
epsonPrinters = [Printer]()
starPrinters = [Printer]()
epson_startSearching()
DispatchQueue.global(qos: .background).async { [unowned self] in
let devices = SMPort.searchPrinter()
self.starPrinters = [devices.map { portInfo -> Printer in
// id, model and portName in below fails with messages like:
// Value of type '[Any]' has no member 'modelName'
let p = Printer(
id: portInfo.modelName,
make: "Star Micronics",
model: portInfo.modelName,
portName: portInfo.portName)
// error on portInfo.modelName
// Value of type '[Any]' has no member 'modelName'
if let name = portInfo.modelName as? String {
p.emulation = name.containsString("TSP143") ? "StarGraphics" : "StarLine"
}
return p
}!]
}
}
I know that I can replace the 'id:...' part with the likes of:
id: ((portInfo[0] as AnyObject).modelName) ?? "",
But this isn't correct because PortInfo can have none, 1 or multiples depending on the number of printers we find.
I'd appreciate any suggestions for refactoring this in an elegant way that is good Swift 3 syntax and likely to survive into Swift 4.
I'm working in Xcode 8.3.2
When you get some errors about types, you'd better check what type each variable has. When you select devices in the line let devices = ..., Quick Help of Xcode will show you something like this:
Declaration let devices: [Any]?
First, it's an Optional and you need to unwrap it, before using the actual content.
Second, the type of the elements in devices is Any, to which you cannot apply any methods (including property accessors). You need to cast it to an appropriate type at an appropriate place.
To solve the two things above, you can write something like this:
guard let devices = SMPort.searchPrinter() as? [PortInfo] else {
fatalError("This may never happen")
}
With guard statement above, Quick Help will show you:
Declaration let devices: [PortInfo]
Non-Optional, simple Array of PortInfo, so you can use any methods of PortInfo for the elements of this devices.
I would translate your Swift 2 code into Swift 3 like this:
func search() {
epsonPrinters = []
starPrinters = []
epson_startSearching()
DispatchQueue.global(qos: .default).async {
guard let devices = SMPort.searchPrinter() as? [PortInfo] else {
fatalError("This may never happen")
}
self.starPrinters = devices.map { portInfo -> Printer in
let p = Printer(
id: portInfo.modelName,
make: "Star Micronics",
model: portInfo.modelName,
portName: portInfo.portName)
if let name = portInfo.modelName {
p.emulation = name.contains("TSP143") ? "StarGraphics" : "StarLine"
}
return p
}
}
}
You may need some fixes (not many, I believe) to use this code, as you are not showing all relevant things such as the definition of Printer.
I am trying to use CMMotionManager to update the attitude of a camera viewpoint in scenekit. I am able to get the following code using the default reference to work.
manager.deviceMotionUpdateInterval = 0.01
manager.startDeviceMotionUpdates(to: motionQueue, withHandler:{ deviceManager, error in
if (deviceManager?.attitude) != nil {
let rotation = deviceManager?.attitude.quaternion
OperationQueue.main.addOperation {
self.cameraNode.rotation = SCNVector4(rotation!.x,rotation!.y,rotation!.z,rotation!.w)
}
}
})
I am however unable to get startDeviceMotionUpdates to work with a selected reference frame as shown below:
manager.deviceMotionUpdateInterval = 0.01
manager.startDeviceMotionUpdates(using: CMAttitudeReferenceFrameXMagneticNorthZVertical, to: motionQueue, withHandler:{ deviceManager, error in
if (deviceManager?.attitude) != nil {
let rotation = deviceManager?.attitude.quaternion
OperationQueue.main.addOperation {
self.cameraNode.rotation = SCNVector4(rotation!.x,rotation!.y,rotation!.z,rotation!.w)
}
}
})
The error i receive is:
Use of unresolved identifier 'CMAttitudeReferenceFrameXMagneticNorthZVertical'
I get similar error messages for other reference frames as well. Can anyone shed any light on the use of the "using:" parameter for the startDeviceMotionUpdates function? All the examples i have found are for older versions of swift or objective c so it is quite possible that it is simply an issue with not understanding Swift 3 syntax.
After some additional fiddling i figured out that the using argument expects a member of the new CMAttitudeReferenceFrame struct. i.e. it should be passed as:
manager.deviceMotionUpdateInterval = 0.01
manager.startDeviceMotionUpdates(using: CMAttitudeReferenceFrame.xMagneticNorthZVertical
,to: motionQueue, withHandler:{
deviceManager, error in
if (deviceManager?.attitude) != nil {
let rotation = deviceManager?.attitude.quaternion
OperationQueue.main.addOperation {
self.cameraNode.rotation = SCNVector4(rotation!.x,rotation!.y,rotation!.z,rotation!.w)
}
}
})
This is a change from earlier version that allowed the direct use of constants such as "CMAttitudeReferenceFrameXMagneticNorthZVertical"
I have several text files which I want to transfer between 2 Apps. (ie. free and paid versions of the same App).
I'm using UIPasteboard to do this. The contents of the files are held in memory as NSArrays, and so I want to copy these NSArrays to the pasteboard (lite version), and read them from the pasteboard (full version).
For some reason the data cannot be read back from the pasteboard. The data is being returned as a NSData object, rather than NSArray, which I think means that it is not in the required format for the pasteboard type I am using, which is "public.utf8-plain-text".
When I read/write NSStrings with this pasteboard type, it works fine.
I searched through Apple docs, etc, to see if there is a different type I should be using for NSArrays, (or other property list objects), but drew a blank.
Writing to the pasteboard: (In the following pDataOutput is an array of strings, file contents) :
NSMutableArray *lArrayCopy = [gGlobalData.cPasteBoard.items mutableCopy];
[lArrayCopy replaceObjectAtIndex:pDataFileIdx
withObject:[NSDictionary dictionaryWithObject:pDataOutput
forKey:#"public.utf8-plain-text"]];
gGlobalData.cPasteBoard.items = lArrayCopy;
[lArrayCopy release];
Reading from the pasteboard:
NSArray *lPBItems = [pPasteBoard valuesForPasteboardType:#"public.utf8-plain-text"
inItemSet:nil];
NSLog(#"PB Items = NSArray of count %d", lPBItems.count);
The above returns:
PB Items = NSArray of count 0
As mentioned above, it returns the data correctly as NSStrings if written as NSStrings.
Any help would be very much appreciated.
Thanks
Stephen C
I ran into the same issue and I think the valueForPasteboardType family of methods are broken and always return NSData.
Here is my solution:
NSArray * lArrayFromPasteBoard = [pPasteBoard valueForPasteboardType:#"com.my.custom.type"];
if ([lArrayFromPasteBoard isKindOf:[NSData class]])
{
lArrayFromPasteBoard = [[NSPropertyListSerialization propertyListWithData:(NSData*)lArrayFromPasteBoard options:0 format:0 error:0];
}
hopefully this will make it so the code in the if won't get called anymore once apple fixes their bug
As of iOS 8.3, UIPasteboard still has this bug. I wrote an extension for UIPasteboard to handle this:
extension UIPasteboard {
func arrayForPasteboardType(pasteboardType: String) -> NSArray? {
switch valueForPasteboardType(pasteboardType) {
case let array as NSArray:
return array
case let data as NSData:
if let array = NSPropertyListSerialization.propertyListWithData(data, options: 0, format: nil, error: nil) as? NSArray {
return array
}
default:
break
}
return nil
}
}