I am trying to get string from string file called "Common.strings" that I have created to store some non translated strings like URLs and names.
So, to do that I created the a strings file called "Common":
I find the way using localizedString like below:
Bundle.main.localizedString(forKey: "api_url", value: "", table: "Common")
There are another way to do that ? The code that I am using is right ?
I am asking cause I don't want a "localized" string
Declare the constant values as such in code, there is no need to create a .strings file.
E.g. let urlString = "http://mywebsite.com"
You could also put it inside a struct to effectively namespace your constants:
struct Constants {
static let urlString = "http://www.mywebsite.com"
}
Giving you something like: let baseUrlString = Constants.urlString
Related
How do I use Storage in Vapor 4?
I tried the following:
if let someValue = req.storage.get(theKey) as? String {
// do something
} else {
req.storage.set(theKey, to: "Some Value")
}
However I get the following Errors:
error: type of expression is ambiguous without more context
if let original: String = req.storage.get(theKey) {
~~~~~~~~~~~~^~~~~~~~~~~
error: type of expression is ambiguous without more context
req.storage.set(theKey, to: "Some Value")
~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I also did not find any documentation on this topic.
The input key is actually a Protocol use must implement. If you want to see examples of how Store is used, do like #imike says and look for usages of the Storage class.
Storage is not string based key object storage. You have to declare a struct conforming to StorageKey, implement the typealias Value representing the object type you want to store.
If you need to store a string let's take this example :
struct MyStringKey: StorageKey {
typealias Value = String
}
...
request.storage.set(MyStringKey.self, to: "my string")
var myString: String? = request.storage.get(MyStringKey.self)
It is NOT possible for the Key to be any arbitrary String. The key must be predefined.
I have seen some people declaring constant file using Struct like this:
Approach 1:
struct Constants {
struct UserInfoParam {
static let userName = "user_name"
static let userID = "user_id"
}
}
And call it like this:
print(Constants.UserInfoParam.userName)
Approach 2:
And some people directly create a Swift file and simply declare the variables, like:
import Foundation
let userName = "user_name"
let userID = "user_id"
And call it simply like this:
print(userID)
I want to know which approach is best to implement for Code Quality and Other Coding aspects. Can someone clarify me this?
Thanks in Advance.
Coding style depends on person to person, so here it also depends on you and your requirement.
For example with Approach 1, you can categorize your constants. Check,
struct Constants {
struct UserInfoParam {
static let userName = "user_name"
static let userID = "user_id"
}
struct API {
static let api1 = "api1"
static let api2 = "api2"
}
struct AlertMessages {
static let NoDataFound = "No Data Found."
static let InternetError = "Check internet connection."
}
}
In the above approach, personally I prefer not to use Constants struct, as it just increasing the struct hierarchy.
So I did like this,
struct UserInfoParam {
:
}
struct API {
:
}
struct AlertMessages {
:
}
Now whenever need I just write AlertMessages.NoDataFound instead of Constants.AlertMessages.NoDataFound. These both way are correct and you can try anyone.
But when you talked about Approach2, then you can use it for some general constants.
For Eg.
let Base_URL = "Base URL"
let ItunesAppId = "ID"
so on.
These objects globally used, even in the Constants struct too. These vars are not belonging to any category.
In these ways generally developer did code.
see apple / swift docs. (https://docs.swift.org/swift-book/LanguageGuide/TheBasics.html )
they simply say:
Declaring Constants and Variables
Constants and variables must be declared before they’re used. You declare constants with the let keyword and variables with the var keyword. Here’s an example of how constants and variables can be used to track the number of login attempts a user has made:
let maximumNumberOfLoginAttempts = 10
var currentLoginAttempt = 0
so no need to struct.
Can be questionable if wee have to share const in multiple files...
I will say myst be very few... and public (default access is fine)
I'm trying to initialise a value in dictionary as follow,
var og:image: String
But after og: it tries to assign the type considering og as the variable to site_name, which is obviously wrong.
Is there a way to assign og:image as variable to String type using
special or escape characters?
In reference to this, apple does not provide any meaningful explanations to variable naming conventions in such a situation.
Edit-1:
Here is code snippet to clarify dictionary usage is in JSON parsing data structure,
struct Metadata: Decodable{
var metatags : [enclosedTags]
}
struct enclosedTags: Decodable{
var image: String
var title: String
var description: String
var og:site_name: String
}
You cannot use : (colon). But if you really want:
var ogCOLONimage: String
Joking apart. You could use a Dictionary or something like that:
var images: [String: String] = ["og:image" : "your string"]
Now you can access your og:image data with images["og:image"].
Swift allow you to use almost any character when naming variables. You can even use Unicode characters.
However, there are a few restrictions:
Constant and variable names can’t contain whitespace characters, mathematical symbols, arrows, private-use (or invalid) Unicode code points, or line- and box-drawing characters. Nor can they begin with a number, although numbers may be included elsewhere within the name.
Said that, it is not possible to use : in the name of a variable. However, you can use a Unicode character similar to that symbol. Depending on what you want it for, this may be a valid solution.
Here you have a list of the Unicode characters similar to : that can be used in the name of a variable:
︓
﹕
：
(https://www.compart.com/en/unicode/based/U+003A)
Based on the example you provided it would be this:
struct Metadata: Decodable{
var metatags : [enclosedTags]
}
struct enclosedTags: Decodable{
var image: String
var title: String
var description: String
var og：site_name: String
}
Turns out swift has it's own feature in terms of naming specificity of variables in structs i.e. CodingKeys, so in terms for me the below naming convention worked,
struct Metadata: Decodable{
var metatags: [enclosedTags]
}
struct enclosedTags: Decodable{
let image: String
let title: String
let description: String
let siteName: String
private enum CodingKeys : String, CodingKey{
case image = "og:image", title = "og:title", description = "og:description", siteName = "og:site_name"
}
This was rightfully pointed out by #hamish in comments (Thanks mate!)
Hello I have a for in loop where elements is the variable being changed and in this case "elements" is a string but there is a corresponding variable out side of the for in loop that has the same name as the string called elements. So what I mean is out side there is a Var time = [some,text,words] and theres a for in loop that calls a STRING named "time" and I would like to know how to convert the string in the for in loop into the variable by some how taking off the "'s (not that simple I know) without specifically saying "time"(the variable) but instead converting the "elements"(which is the string 'time') string into the variable. I hope I was clear enough if I'm not making sense I'll try again.
You cannot refer to local variables dynamically by their names in Swift. This would break a lot of compiler optimizations as well as type safety if you could.
You can refer to object properties by their names if the class conforms to key-value coding. For example:
class X : NSObject {
let time = ["some", "text", "words"]
func readWordsFromProp(name: String) -> String {
guard let list = self.valueForKey(name) as? [String] else {
return ""
}
var result = ""
for word in list {
result += word
}
return result
}
}
let x = X()
print(x.readWordsFromProp("time"))
In general, there are better ways to do things in Swift using closures that don't rely on fragile name-matching. But KVC can be a very powerful tool
I had some older Swift code that used to compile and work where I was using the .append to build out a data structure dynamically. After upgrading to a few compiler versions newer I am getting the dreaded "Extra Argument ' ' in call" error. I reduced the code down to this:
struct EHSearch {
let EHcategory : String = ""
let EHname : String = ""
}
var myEHSearch = [EHSearch]()
// Call to dynamically append the results
// Extra argument: 'EHcategory' in call
myEHSearch.append(EHSearch(EHcategory: "Food", EHname: "Joes Crab Shack"))
I can't see anything so far in searching on what has changed to cause this one so seeking guidance here.
Because you have let in your struct.
Define your structure like this:
struct EHSearch {
var EHcategory : String = ""
var EHname : String = ""
}
If you have constants in your struct, you can not provide them initial value while creating new structure instances. The automatically-generated member-wise initializer doesn't accept let members as parameters of the initializer of struct.
It depends on your intentions with the struct's properties. Do you want them to be mutable or not?
If yes, then #sasquatch's answer will do.
If not, then you need to ensure a value is assigned to them only once. As you already do that in the struct declaration (the default values), you can't assign new values to them. But being a struct, they don't need to have default values - moreover, struct automatically receive a memberwise initializer. https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/Initialization.html
So here is the variant for immutable properties:
struct EHSearch {
let EHcategory : String
let EHname : String
}
var myEHSearch = [EHSearch]()
// Call to dynamically append the results
// Extra argument: 'EHcategory' in call
myEHSearch.append(EHSearch(EHcategory: "Food", EHname: "Joes Crab Shack"))
The "Extra Argument" error you're seeing is because the compiler already has values for the properties so it doesn't expect any new ones. Here is the "middle" way - one property has a default value whilst the other doesn't - which should make it clearer:
struct EHSearch {
let EHcategory : String = ""
let EHname : String
}
var myEHSearch = [EHSearch]()
// Call to dynamically append the results
// Extra argument: 'EHcategory' in call
myEHSearch.append(EHSearch(EHname: "Joes Crab Shack"))