Runtime方法交换

首先创建两个类 每一个类里面都创建一个方法
例如：类1
@interface classOne : NSObject

• (void)methodOne;
  @end
  @implementation classOne
• (void)methodOne {
  NSLog(@"methodOne");
  }
  @end

类2
@interface classTwo : NSObject

• (void)methodTwo;
  @end
  @implementation classTwo

• (void)methodTwo {
  NSLog(@"methodTwo");
  }
  @end
  交换方法
  @implementation ViewController

• (void)viewDidLoad {
  [super viewDidLoad];
  // NSLog(@"host====%s",KsearchHost);
  Method method1 = class_getInstanceMethod([classTwo class], @selector(methodTwo));
  Method method2 = class_getInstanceMethod([classOne class], @selector(methodOne));
  method_exchangeImplementations(method1, method2);
  [[classOne new] methodOne];

   // Do any additional setup after loading the view, typically from a nib.
  

}
@end

//输出结果是methodTwo 已经实现了方法的交换