Profile your Swift code when you're too lazy to use Instruments

QuickProfiling.swift

// Profile your code when you're too lazy to use Instruments

// Method one: get the time to execute a block
func getTimeToExecute(block: () throws -> Void) rethrows -> NSTimeInterval {
    let start = NSDate().timeIntervalSince1970
    try block()
    return NSDate().timeIntervalSince1970 - start
}

// example:
let time = getTimeToExecute {
  someLongRunningFunction()
}
print("Execution took \(time) seconds")


// Method two: profile a named block inline (shorthand) 
func profile(name: String, block: () throws -> Void) rethrows {
    let time = try getTimeToExecute(block)
    print("Profiling: \(name) took \(Int(time * 1000)) ms")
}

// example:
profile("longRunningFunction") {
  longRunningFunction()
}


// Method three: profile something that you don't want to put into a closure
typealias ProfilingToken = String
var profilingMap: [ProfilingToken: (name: String, startTime: NSTimeInterval)] = [:]
func startProfiling(name: String) -> ProfilingToken {
    let token = ProfilingToken(NSUUID().UUIDString)
    profilingMap[token] = (name: name, startTime: NSDate().timeIntervalSince1970)
    return token
}
func stopProfiling(profilingToken: ProfilingToken) {
    let endTime = NSDate().timeIntervalSince1970
    if let tuple = profilingMap[profilingToken] {
        let time = endTime - tuple.startTime
        print("Profiling: \(tuple.name) took \(Int(time * 1000)) ms")
    }
}

// example:
let token = startProfiling("some statements I want to be able to move around easily")
func1()
func2()
func3()
func4()
func5()
stopProfiling(token)

// Method 3.5: simple method profiling with defer
func viewWillAppear() {
  super.viewWillAppear()
  
  let token = startProfiling("MyViewController#viewWillAppear")
  defer { stopProfiling(token) }
  
  // All your really,
  // really,
  // really,
  // really...
  // really long code goes here
}