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VisualizaçõesUsing closures as parameters without trailing closures Swift
When using trailing closure syntax it seems quite easy to pass a function as a parameter of another function.
However I want to do this WITHOUT using the trailing closure syntax
func doSomethingTwo(closure: (String) -> Void) {
closure("AAA")
}
doSomethingTwo(closure: print("TEST") )
gives Cannot convert value of type '()' to expected argument type '(String) -> Void'
I know that
doSomethingTwo{ (test: String) in
print ("\(test)")
}
works, but want this without the trailing closure syntax.
This is not a homework problem, I am looking at tutorials and have done research that has not given me an answer to this question.
3 Respostas
Responde à pergunta0
You need to define your own print method to pass it as a parameter:
func doSomethingTwo(closure: (String) -> ()) {
// when you call the closure you need to pass the string to be printed
closure("TEST")
}
Define the method to print the string that will be passed to the closure:
let closure: (String) -> () = { print($0) }
Then you can call it as you wish:
doSomethingTwo(closure: closure)
0
This is how you call a function
doSomethingTwo()
If we follow the pattern, put () first, then comes with its parameter, you'll get something like this.
doSomethingTwo(closure: { (str) in
print(str)
})
By the way, Xcode will helps you to complete. But if you don't want its help, when you have this, don't tap, type the rest by your own.
0
You're not calling the function correctly. You should call it like this:
doSomethingTwo(closure: { (text) in
print(text)
})