Profiling.swift

import Foundation

public func profiling<R>(label: String, @noescape _ block: () -> R) -> R { 
    NSLog("*** %@...", label) 
    let start = NSDate() 
    defer { 
        let end = NSDate() 
        NSLog("*** %@ took %5.3g seconds", label, end.timeIntervalSinceDate(start)) 
    } 
    return block() 
}

let result: Int? = profiling("heavy computation") {
    NSLog("Really computing hard now")
    return Int("123")
}

// 2015-06-09 22:32:48.811 repl_swift[39408:2024531] *** heavy computation...
// 2015-06-09 22:32:48.811 repl_swift[39408:2024531] Really computing hard now
// 2015-06-09 22:32:48.812 repl_swift[39408:2024531] *** heavy computation took 0.000195 seconds