swift - w3toppers.com

SwiftUI View and @FetchRequest predicate with variable that can change

had the same problem, and a comment of Brad Dillon showed the solution: var predicate:String var wordsRequest : FetchRequest<Word> var words : FetchedResults<Word>{wordsRequest.wrappedValue} init(predicate:String){ self.predicate = predicate self.wordsRequest = FetchRequest(entity: Word.entity(), sortDescriptors: [], predicate: NSPredicate(format: “%K == %@”, #keyPath(Word.character),predicate)) } in this example, you can modify the predicate in the initializer.

Saving CGImageRef to a png file?

Using CGImageDestination and passing kUTTypePNG is the correct approach. Here’s a quick snippet: @import MobileCoreServices; // or `@import CoreServices;` on Mac @import ImageIO; BOOL CGImageWriteToFile(CGImageRef image, NSString *path) { CFURLRef url = (__bridge CFURLRef)[NSURL fileURLWithPath:path]; CGImageDestinationRef destination = CGImageDestinationCreateWithURL(url, kUTTypePNG, 1, NULL); if (!destination) { NSLog(@”Failed to create CGImageDestination for %@”, path); return NO; } … Read more

Keep window always on top?

To change the window level you can’t do it inside viewDidload because view’s window property will always be nil there but it can be done overriding viewDidAppear method or any other method that runs after view is installed in a window (do not use it inside viewDidLoad): Swift 4 or later override func viewDidAppear() { … Read more

How to convert a decimal number to binary in Swift?

You can convert the decimal value to a human-readable binary representation using the String initializer that takes a radix parameter: let num = 22 let str = String(num, radix: 2) print(str) // prints “10110” If you wanted to, you could also pad it with any number of zeroes pretty easily as well: Swift 5 func … Read more

Convert Float to Int in Swift

You can convert Float to Int in Swift like this: var myIntValue:Int = Int(myFloatValue) println “My value is \(myIntValue)” You can also achieve this result with @paulm’s comment: var myIntValue = Int(myFloatValue)

How to append elements into a dictionary in Swift?

You’re using NSDictionary. Unless you explicitly need it to be that type for some reason, I recommend using a Swift dictionary. You can pass a Swift dictionary to any function expecting NSDictionary without any extra work, because Dictionary<> and NSDictionary seamlessly bridge to each other. The advantage of the native Swift way is that the … Read more

Providing a default value for an Optional in Swift?

Update Apple has now added a coalescing operator: var unwrappedValue = optionalValue ?? defaultValue The ternary operator is your friend in this case var unwrappedValue = optionalValue ? optionalValue! : defaultValue You could also provide your own extension for the Optional enum: extension Optional { func or(defaultValue: T) -> T { switch(self) { case .None: … Read more

Calling protocol default implementation from regular method

I don’t know if you are still looking for an answer to this, but the way to do it is to remove the function from the protocol definition, cast your object to Foo and then call the method on it: protocol Foo { // func testPrint() <- comment this out or remove it } extension … Read more

dispatch_once after the Swift 3 GCD API changes

While using lazy initialized globals can make sense for some one time initialization, it doesn’t make sense for other types. It makes a lot of sense to use lazy initialized globals for things like singletons, it doesn’t make a lot of sense for things like guarding a swizzle setup. Here is a Swift 3 style … Read more

Swift Alamofire: How to get the HTTP response status code

For Swift 3.x / Swift 4.0 / Swift 5.0 users with Alamofire >= 4.0 / Alamofire >= 5.0 response.response?.statusCode More verbose example: Alamofire.request(urlString) .responseString { response in print(“Success: \(response.result.isSuccess)”) print(“Response String: \(response.result.value)”) var statusCode = response.response?.statusCode if let error = response.result.error as? AFError { statusCode = error._code // statusCode private switch error { case .invalidURL(let … Read more