Swift 2.0 Study Notes (day 23)--trailing closures

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A closure expression can be passed as a function parameter, and if the closure expression is long, it affects the readability of the program. A trailing closure is a closure expression that is written after the function brackets, and the function supports calling it as the last argument.

Let's look at a sample code:

Func Calculate (opr:string, Funn: (int, int)Int) {//The last parameter, Funn, is the (int,int)-Int function type, Funn can receive a closure expression     Switch(OPR) { Case "+": Print ("+ 5 = \ (Funn (10,5))")    default: Print ("10-5 = \ (Funn (10,5))")}} calculate ("+", Funn: {(A:int, b:int), Intinch returnA + b})//calledCalculate ("+") {(A:int, b:int), Intinch returnA + b}//called, this form is the trailing closureCalculate ("+") { $0+ $1}//called, this form is the trailing closure

It should be noted that the closure must be the last parameter of the parameter list if the Calculate function is defined in the following form:

Func Calculate (funn: (int, int), int, opr:string) {

...

}

Because the closure expression is not the last parameter, the call to the Calculate function cannot be written using a trailing closure.

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Swift 2.0 Study Notes (day 23)--trailing closures