Swift pass block from Objective-C to Swift - objective-c

Question

I have a method in Objective-C that takes a parameter and returns a result in a block. How do I return this result through a bridging header to a swift block? Note I have other non-block functions returning and this works fine.
Objective-C
- (void)performMethod:(NSString*)myString
{
[self.class
doSomething:myString
onSuccess:^(NSArray * results) {
// Return results
}
onFailure:^(NSError * error) {
// Return error
}];
}
Bridging header
?
Swift
class.performMethod(myString:String)->(results) in NSArray {
}

Answer 1

the trouble is that your Objective C function return void, not some block
how to deal with block in swift ? see the example below
// this block takes an Int as parameter and returns an Int
let myBlock: (Int)->Int = { i in
return i
}
let i = myBlock(10)
print(i) // 10
// this block takes no parameters and return an empty Array<Int>
let myBlock2: ()->Array<Int> = { Void in
return [Int]()
}
print(myBlock2.dynamicType) // () -> Array<Int>
let arr = myBlock2()
print(arr, arr.dynamicType) // [] Array<Int>
from what i can see in your code, you try to do something like
import Foundation
func bar(str: String, onSucces: ()-> NSArray, onError: ()->NSError) {
// do something with str
if str == "alfa" {
// success
let arr = onSucces()
print(arr)
} else {
let err = onError()
print(err)
}
}
func foo(str: String) -> Void {
bar(str, onSucces: { () -> NSArray in
return NSArray(array: [str])
}) { () -> NSError in
return NSError(domain: "error", code: -1, userInfo: nil)
}
}
foo("alfa")
/*
(
alfa
)
*/
foo("")
/*
Error Domain=error Code=-1 "(null)"
*/