In Swift 3 contains method is always giving error. In the below code if annotation is MKAnnotation is passed and goest to next line. Then it gives error. I have searched a lot but not able to find the problem. Any solution for this issue?
Class declaration:
open class FBAnnotation : NSObject {
open var coordinate = CLLocationCoordinate2D(latitude: 52.0936440, longitude: 4.3592340)
open var title: String? = ""
open var annotationIndex: Int?
}
extension FBAnnotation : MKAnnotation {
}
Usage:
do {
if annotation is MKAnnotation {
if try node.annotations.contains(where: annotation as! (MKAnnotation) throws -> Bool) {
try node.annotations.remove(at: node.annotations.index(where: annotation as! (MKAnnotation) throws -> Bool)!)
node.count -= 1
return true
}
}
} catch {
return false
}
This works in a playground, no casting required. You cannot pass an annotation as the where parameter. You must pass in a function that declares whether or not the annotation is the one you are looking for. Here I consider them a match if they have the same coordinates, although your match criteria may be different.
var annotations = [MKAnnotation]()
var annotation: Any? = nil
if let annotation = annotation as? MKAnnotation {
if let index = annotations.index(where: {
$0.coordinate.latitude == annotation.coordinate.latitude &&
$0.coordinate.longitude == annotation.coordinate.longitude
}) {
annotations.remove(at: index)
}
}
Related
We know how to expose Swift enums to Obj-C:
#objc enum Animal: Int {
case Cat, Dog
}
But the compiler complains that the following "cannot be represented in Obj-C":
func myAnimal() -> Animal? {
if hasPet() {
return .Cat
} else {
return nil
}
}
Ideas?
Optional Ints in Swift don't map to a type in Objective-C. The issue is that your myAnimal() method is returning a type that can't be represented in Objective-C.
The way I see it, you have two options...
Option1: Change your method's return type:
func myAnimal() -> NSNumber? {
// method body goes here.
}
This doesn't really seem great since in Objective-C you'd have to do something like this:
if (myAnimal().integerValue == AnimalCat) {
// do stuff here
}
Option 2: Add a catch-all case in your enum
#objc enum Animal: Int {
case none = 0
case cat = 1
case dog = 2
init(rawValue: Int) {
switch rawValue {
case 1: self = Cat
case 2: self = Dog
default: self = None
}
}
}
// Updated method signature that makes the compiler happy.
func myAnimal() -> Animal {
if hasPet() {
return .Cat
} else {
return .None
}
}
This way, you can change your method signature to not return an optional, and the compiler will be happy.
I have this code working fine in Swift 2.
extension PHFetchResult: Sequence {
public func makeIterator() -> NSFastEnumerationIterator {
return NSFastEnumerationIterator(self)
}
}
Since I upgraded to Swift 3
Extension of a generic Objective-C class cannot access the class's generic parameters at runtime
I have no idea on how to fix this. Any help is much appreciated!
Problem was reported here: https://bugs.swift.org/browse/SR-1576
But in the end you can't use for in with PHFetchResult in Swift 3.0. Let's see some examples:
let collections = PHAssetCollection.fetchAssetCollections(with: .album, subtype: .any, options: nil)
let collectionLists = PHCollectionList.fetchCollectionLists(with: .momentList, subtype: .momentListYear, options: nil)
let assets = PHAsset.fetchAssets(with: .image, options: nil)
You can either use the built-in enumeration of PHFetchResult (my recommended solution):
collections.enumerateObjects(_:) { (collection, count, stop) in
//...
}
collectionLists.enumerateObjects(_:) { (collectionList, count, stop) in
//...
}
assets.enumerateObjects(_:) { (asset, count, stop) in
//...
}
Or access each object by its index:
for idx in 0 ..< collections.count {
let collection = collections[idx]
// ...
}
for idx in 0 ..< collectionLists.count {
let collectionList = collectionLists[idx]
// ...
}
for idx in 0 ..< assets.count {
let asset = assets[idx]
// ...
}
Pulling from Realm, you may be able to get around this by extending a subclass of what you want to conform to Sequence and put the makeIerator function there.
// Sequence conformance for ClassA is provided by ProtocolX's `makeIterator()` implementation.
extension ClassA: Sequence {}
extension ProtocolX {
// Support Sequence-style enumeration
public func makeIterator() -> RLMIterator {
return RLMIterator(collection: self)
}
}
You can see the full code at https://github.com/realm/realm-cocoa/blob/master/Realm/Swift/RLMSupport.swift
You can use a wrapper type as suggested by Swift engineer Jordan Rose on the bug report:
import Photos
struct ResultSequence<Element: AnyObject>: Sequence {
var result: PHFetchResult<Element>
init(_ result: PHFetchResult<Element>) {
self.result = result
}
func makeIterator() -> NSFastEnumerationIterator {
return NSFastEnumerationIterator(self.result)
}
}
func test(_ request: PHFetchResult<PHCollection>) {
for elem in ResultSequence(request) {
print(elem)
}
}
There is no way to fix that, you might need to refactor your code or use some other techniques.
you can refer to this:
How to use a swift class with a generic type in objective c
docs:
https://developer.apple.com/library/content/documentation/Swift/Conceptual/BuildingCocoaApps/MixandMatch.html#//apple_ref/doc/uid/TP40014216-CH10-XID_78
I have API request to get json string, something like that:
{
"data":[
{
"id":123,
"name":"Felix"},
{
"id":122,
"name":"Mary"},
{
"id":111,
"name":"Jason"},
]
}
and in my Obj-C NSDictionary+user is
-(NSString *)usrId
{
return self[#"id"];
}
-(NSString *)usrName
{
return self[#"name"];
}
...
and when I use this I import the category class, and access it like dict.name...
I can't find a good answer related to this question. How can I achieve this in Swift?
UPDATED [2017.07.21]
I've chose to use SwiftyJSON library to settle all the json-dictionary-object-mapping works. Save tons of time.
SwiftyJSON
Best and safest way to parse json response to nsdictionary and use it in swift is:
var responseRecord<datastruct> = Array<datastruct>()
struct datastruct
{
var id: String?
var name:String?
init(add: NSDictionary)
{
id = add["id"] as? String
name = add["name"] as? String
}
}
And to access it in program:
print(self.responseRecord.id)
print(self.responseRecord.name)
Simply create a empty Swift class with required properties (Swift 2.2):-
class myClass {
var id:Int?
var name:String?
init(id:Int,name:String)
{
self.id= id
self.name = name
}
}
Then to access in required VC :-
var requiredData:[String]?
var data:[myClass]?
override fun viewDidLoad()
{
super.viewDidLoad()
requiredData = data!.enumerate().map({ (index, category) in
return ("\(category.name!)")
})
print(requiredData)
}
Note: I am assuming you have already populated data in the mentioned "data" variable of myClass type. If not, then you can do so as follows:-
data = [myClass(id:1,name:"aaa"),myClass(id:2,name:"bob"),myClass(id:3,name:"ccc")]
I have some experience in ObjC and I just started learning Swift. In Objc everything is a class through #interface in .h and #implementation of .m, or in other Swift classes that I have seen everything is usually in some form of
class MyCustomClassInhertingfrom: SomeFoundationClass { //methods & properties}
Yet here in some class named pancakeHouse.Swift there is no mention of the keyword class WHY? Isn't this a Model Class? Doesn't this break the MVC design pattern? Is this happening because of new powerful features of enums& structs vs class in Swift?_____I am confused obviously!
import UIKit
import CoreLocation
enum PriceGuide : Int {
case Unknown = 0
case Low = 1
case Medium = 2
case High = 3
}
extension PriceGuide : CustomStringConvertible {
var description : String {
switch self {
case .Unknown:
return "?"
case .Low:
return "$"
case .Medium:
return "$$"
case .High:
return "$$$"
}
}
}
enum PancakeRating {
case Unknown
case Rating(Int)
}
extension PancakeRating {
init?(value: Int) {
if value > 0 && value <= 5 {
self = .Rating(value)
} else {
self = .Unknown
}
}
}
extension PancakeRating {
var ratingImage : UIImage? {
guard let baseName = ratingImageName else {
return nil
}
return UIImage(named: baseName)
}
var smallRatingImage : UIImage? {
guard let baseName = ratingImageName else {
return nil
}
return UIImage(named: "\(baseName)_small")
}
private var ratingImageName : String? {
switch self {
case .Unknown:
return nil
case .Rating(let value):
return "pancake_rate_\(value)"
}
}
}
struct PancakeHouse {
let name: String
let photo: UIImage?
let thumbnail: UIImage?
let priceGuide: PriceGuide
let location: CLLocationCoordinate2D?
let details: String
let rating: PancakeRating
}
extension PancakeHouse {
init?(dict: [String : AnyObject]) {
guard let name = dict["name"] as? String,
let priceGuideRaw = dict["priceGuide"] as? Int,
let priceGuide = PriceGuide(rawValue: priceGuideRaw),
let details = dict["details"] as? String,
let ratingRaw = dict["rating"] as? Int,
let rating = PancakeRating(value: ratingRaw) else {
return nil
}
self.name = name
self.priceGuide = priceGuide
self.details = details
self.rating = rating
if let imageName = dict["imageName"] as? String where !imageName.isEmpty {
photo = UIImage(named: imageName)
} else {
photo = nil
}
if let thumbnailName = dict["thumbnailName"] as? String where !thumbnailName.isEmpty {
thumbnail = UIImage(named: thumbnailName)
} else {
thumbnail = nil
}
if let latitude = dict["latitude"] as? Double,
let longitude = dict["longitude"] as? Double {
location = CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
} else {
location = nil
}
}
}
extension PancakeHouse {
static func loadDefaultPancakeHouses() -> [PancakeHouse]? {
return self.loadPancakeHousesFromPlistNamed("pancake_houses")
}
static func loadPancakeHousesFromPlistNamed(plistName: String) -> [PancakeHouse]? {
guard let path = NSBundle.mainBundle().pathForResource(plistName, ofType: "plist"),
let array = NSArray(contentsOfFile: path) as? [[String : AnyObject]] else {
return nil
}
return array.map { PancakeHouse(dict: $0) }
.filter { $0 != nil }
.map { $0! }
}
}
extension PancakeHouse : CustomStringConvertible {
var description : String {
return "\(name) :: \(details)"
}
}
extension PancakeHouse: Equatable {
}
func ==(lhs: PancakeHouse, rhs: PancakeHouse) -> Bool {
return lhs.name == rhs.name
}
Note: I would appreciate an answer that also includes comparison of the .swift vs .h + .m ie don't just consider this as a specific question, consider it as a general question and explain or link the prerequisites's details needed to understand this question)
pancakeHouse.swift defines PancakeHouse and all the various things that go with it. That is perfectly good Swift style. There is no class here because PancakeHouse happens to be a struct, which is also perfectly good Swift style (and mildly preferred). Structs are much like classes in Swift, in that they can have data and methods (and extensions).
ObjC does not require that each class be defined in its own .h/.m pair, but it is fairly typical ObjC style to do so. That said, even in ObjC there are exceptions. It is common to have mutable subclasses defined in the same file as their base class (NSArray and NSMutableArray are both defined in NSArray.h). Swift style has evolved towards lumping related things together more closely. One style makes it easier to find something if you know its name. The other makes it easier to find related concepts together. Both have their advantages, and once people are used to one they tend to believe that that one is obviously correct. But they're just different ways of organizing.
Note that this file also makes use of Swift extensions to break up related methods. That is also common and good Swift. Old ObjC did that with categories, but it's much less common to organize ObjC code that way today (categories are used for other things now). Again, neither is deeply correct. It's just the styles that have evolved.
Swift files just need valid swift code. That's all. In this case, your swift file is just defining two enums. Generally it's better practice to put each enum (and its extension) in it's own .swift file, but that's really just personal opinion when you get right down to it.
A .m is the implementation of the .h interface. It's a pain in the !##$ to keep those two things always up to date. Swift makes this much easier by just merging them into one thing/file, and your entire project automatically sees it based on the access you've set. If you don't set any access, like the example above, then you have 'internal' which means the whole project.
There are two philosophies the compiler writers could take on this question:
Each public class needs a file with the matching name - this is Java's way of doing it. Although it is minimally restrictive, the logic behind it is to let the compiler find class references without looking through all the files. It also helps programmers organize their code.
Do it your own way - this is the road taken by Swift, along with C, C#, Objective-C. Essentially, compiler writers tell you that their compiler will find your classes no matter where you put them, letting you organize your code in a way that you find the most intuitive for you and your team.
I can´t get the object properties when retrieving an object from Parse Data Browser. This happened after I changed from "#NSManaged var friends" to "dynamic var friends". Even "name" show nil in User.logInWithUsernameInBackground block which is crazy because the login succeeds. The ACL for User is set to "public read".
User object:
class User : PFUser, PFSubclassing {
dynamic var friends:[User]!
dynamic var name:String!
override class func load() {
self.registerSubclass()
}
}
Retrieving the User along with the friends. println showing nil
var query = User.query()
query.includeKey("friends")
query.getObjectInBackgroundWithId(currentUser.objectId) {
(pfObject: PFObject!, error: NSError!) -> Void in
if pfObject != nil {
var user = pfObject as User
var friends = user.friends as [User]
println("friends: \(friends)") //nil
} else {
println(error)
}
}
Login. println showing nil
User.logInWithUsernameInBackground(USERNAME, password:PASSWORD) {
(user: PFUser!, error: NSError!) -> Void in
if user != nil {
println("Logged in with user: \(user.name)") //nil
} else {
println(error)
}
}
Looking a little deeper for you, it seems the hurdle is a misunderstanding of what the dynamic modifier in Swift does. Apparently, dynamic in Swift is used for Key-Value observing, not declaring a variable's accessors to be defined at runtime (what #dynamic does in Objective-C)
See this for a description of dynamic in Swift https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/BuildingCocoaApps/AdoptingCocoaDesignPatterns.html#//apple_ref/doc/uid/TP40014216-CH7-XID_8
and this for the description of why #NSManaged works the way #dynamic does in Objective-C
https://developer.apple.com/library/prerelease/mac/documentation/Swift/Conceptual/BuildingCocoaApps/WritingSwiftClassesWithObjective-CBehavior.html#//apple_ref/doc/uid/TP40014216-CH5-XID_66
With xCode 6.1.1 I was able to get this working without the bridging header but I did need to use #NSManaged. Here's how... Just:
import Parse
at the top of the calling module. For the class declaration .swift file dynamic didn't work so I needed to use #NSManaged for the variable types to get them to link to the Parse class variables successfully. Like this:
class PSCategory : PFObject, PFSubclassing {
override class func load() {
self.registerSubclass()
}
class func parseClassName() -> String! {
return "Category"
}
#NSManaged var Name: String
}
Then in my query all the names are dynamically linked:
var query = PSCategory.query() // PFQuery(className: "Category")
query.cachePolicy = kPFCachePolicyCacheElseNetwork // kPFCachePolicyNetworkElseCache
query.maxCacheAge = 60 * 60 * 24 // One day, in seconds.
query.findObjectsInBackgroundWithBlock {
(categories: [AnyObject]!, error: NSError!) -> Void in
if error == nil {
for abstractCategory in categories {
let category = abstractCategory as PSCategory
NSLog("Category Name: %#", category.Name)
}
} else {
NSLog("Unable to retrieve categories from local cache or network")
}
}