Log Method Trace

LogTrace.m

#import <Foundation/Foundation.h>
#import <dlfcn.h>

void logTrace(BOOL on) {
    typedef void functype(BOOL);
    void *libobjc = dlopen("/usr/lib/libobjc.dylib", RTLD_LAZY);
    functype *instrumentObjcMessageSends = dlsym(libobjc, "instrumentObjcMessageSends");
    if (!instrumentObjcMessageSends) {
        NSLog(@"Couldn't get instrumentObjcMessageSends");
        exit(1);
    }
    instrumentObjcMessageSends(on);
    NSLog(@"Logging enabled");
}

/*

  This will log all class and instance methods to a file.
  The file is output in /tmp/msgSends-<PID>
  This works on the simulator.
  
  Tested on Xcode 8.3 iOS 10.3 

*/

LogTrace.swift

import Foundation

func logTrace(on: ObjCBool) {
    let libobjc: UnsafeMutableRawPointer = dlopen("/usr/lib/libobjc.dylib", RTLD_LAZY)
    guard let sym = dlsym(libobjc, "instrumentObjcMessageSends") else {
        print("Could not find instrumentObjcMessageSends")
        exit(1)
    }
    typealias instrumentObjcMessageSendsFunc = @convention(c) (_ on: ObjCBool) -> Int
    let f = unsafeBitCast(sym,to: instrumentObjcMessageSendsFunc.self)
    _ = f(on)
    print("Logging enabled")
}

/*

  This will log all class and instance methods to a file.
  The file is output in /tmp/msgSends-<PID>
  This works on the simulator.
  
  Tested on Xcode 8.3 iOS 10.3 

*/