swift中的函数做参数和函数做返回值

函数:

/// 参+返回值func printString(_ A: String) -> Bool {    print(A)    return true}/// 普通参数 + 函数参数 - 返回值func printString(_ B: String, f: (String) -> Bool) -> Bool {    print(B)    return f("func f string is " + B)}/// 无参 - 函数返回值func printString() -> (String) -> Bool {    return printString}/// 函数参 - 无返回值func printString(f: (String) -> ()) {    f("hehe")}/// 闭包中执行的函数参数(逃逸闭包)func printFunc(f: @escaping () -> ()) {    printString { _ in        f()    }}

调用:

_ = printString()_ = printString("print A")_ = printString("print B") { (C: String) -> Bool in    print(C)    return false}printString { (D: String) in    print(D)}printFunc {    print("func")}