CODEWITHSUNDEEP
iosswift
Antonio Romano
Antonio Romano

Reputation: 285

Swift: execution of a function as parameter

I'm trying to accomplish the following task (using the playground): store in an array a list of functions and later execute them.

What I'm doing is:

func f1(){
    println("f1")
}

var a : [(a: Int, b: (Void) -> Void)] = []

a.append(a: 2, b: f1)

for(var i = a.count-1; i >= 0; i--){
    a[i].b()
}

The error I'm getting is the following: "Execution was interrupted, reason: EXC_BAD_ACCESS (code=EXC_I386_GPFLT)" just on the call:

a[i].b()

while if I type: 

a[i].b

Playground suggest me: "(Function)"

Any idea on how I could do this? How could I execute the function? Thanks

Even though Swift seems to prefer the Unnamed tuples the problem seems to be solved with the new Swift version 1.2 (In my tests that worked only with unnamed tuples)

Upvotes: 3

Views: 257

Answers (1)

Antonio
Antonio

Reputation: 72750

That definitely smells like a bug. Decomposing the expression it runs without problems in storyboard:

for(var i = a.count-1; i >= 0; i--){
    let element = a[i]
    let method = element.b
    method()
}

It's probably something related to closures when used in tuples.

I verified that removing the integer value from the tuple, it works:

var a : [((Void) -> Void)] = []

a.append(f1)

for(var i = a.count-1; i >= 0; i--){
    a[i].0()
}

Inverting the order (closure first, integer last) has no effect instead.

Upvotes: 1

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