I came across an article about extension of Optional (https://useyourloaf.com/blog/empty-strings-in-swift/), but I cannot get it to work for the Optional extension.
extension Optional where Wrapped == String {
var isBlank: Bool {
return self?.isBlank ?? true
}
}
func testIsBlank() {
for s in [nil, "", " ", "\t", "abc"] {
print(s?.isBlank)
}
}
For nil value, the output is still nil. I see the article is quite old dated back in 2019. There must be some changes in the language specs. What's going on here?
imneo
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I have a checkbox button in a table column (of course in a NSTableCellView).
@IBAction func check_click(_ sender: Any) {
// How do I know in which row this event occurred?
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}
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set { cache[name] = newValue }
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}
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private var queryItems_: [URLQueryItem]?
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get {
if queryItems_ == nil {
if !queries.isEmpty {
queryItems_ = queries.map { (key: String, value: String?) in
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}
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}
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I don't have any idea why.
import Foundation
struct Dummy: NSObject { // Error: Inheritance from non-protocol type 'NSObject'
var name: String?
}
I have the following code:
let obj: LanguageItem? = LanguageItem(language: "zh-CN")
// Argument type 'LanguageItem?' does not conform to expected type 'CVarArg'
print(String(format:"obj: %@", obj))
struct LanguageItem: Codable
{
var language: String
var name: String?
}
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How to avoid this with my own class objects?
let obj: LanguageItem? = LanguageItem(language: "en")
print("object: \(obj)")
struct LanguageItem: Codable
{
var language: String
var name: String?
}
extension LanguageItem: CustomStringConvertible {
var description: String {
"Lang:\(language) name:\(name ?? "(none)")"
}
}
The print statement still prints "Optional(Lang:en name:(none))". How to get rid the Optional prefix?