ViewController+Swizzle

ViewController+Swizzle.h

//
//  ViewController+Swizzle.h
//  TryingOutStuff
//

#import "ViewController.h"

@interface ViewController (Swizzle)

@end

ViewController+Swizzle.m

//
//  ViewController+Swizzle.m
//  TryingOutStuff
//

#import "ViewController+Swizzle.h"
#import <objc/runtime.h>

@implementation ViewController (Swizzle)

- (void) swizzle_viewDidLoad {
    NSLog(@"I am swizzling view Did Load!!");
    [self swizzle_viewDidLoad];
    
    IMP instanceForDoSomething = [ViewController instanceMethodForSelector:@selector(dosSomethingWith:)];
    void (*func)(id,SEL,...) = (void *)instanceForDoSomething;
    func(self,@selector(dosSomethingWith:),@"this thing");
}

+ (void) load {
    Method original, swizzled;
    original = class_getInstanceMethod(self, @selector(viewDidLoad));
    swizzled = class_getInstanceMethod(self, @selector(swizzle_viewDidLoad));
    method_exchangeImplementations(original, swizzled);
    
    
}

-(void) dosSomethingWith:(NSString *)message {
    NSLog(@"Doing something with : %@",message);
}

@end