iOS OC 消息转发

た入场券 2021-12-15 16:19 372阅读 0赞

#import "ViewController.h"
    #import "Preson.h"
    #import <objc/runtime.h>
    #import <objc/message.h>
    
    @interface ViewController ()
    
    @end
    
    @implementation ViewController
    
    - (void)viewDidLoad {
        [super viewDidLoad];
        [self performSelector:@selector(foo)];
        // Do any additional setup after loading the view.
    }
    
    
    //1.动态方法解析
    +(BOOL)resolveInstanceMethod:(SEL)sel{
        
    
        
        if (sel == @selector(foo)) {
            class_addMethod([self class], sel, (IMP)foo, "v@:");
            return YES;
        }
        
        return [super resolveInstanceMethod:sel];
    }
    
    
    //2.备用接收者
    -(id)forwardingTargetForSelector:(SEL)aSelector{
        if (aSelector == @selector(foo)) {
            return [Preson new];
        }
        return [super forwardingTargetForSelector:aSelector];
    }
    
    //3.完整消息转发
    -(NSMethodSignature*)methodSignatureForSelector:(SEL)aSelector{
        if ([NSStringFromSelector(aSelector) isEqualToString:@"foo"]) {
            return [NSMethodSignature signatureWithObjCTypes:"v@:"];
        }
        return [super methodSignatureForSelector:aSelector];
    }
    
    
    - (void)forwardInvocation:(NSInvocation *)anInvocation {
        SEL sel = anInvocation.selector;
        Preson *p = [Preson new];
        if([p respondsToSelector:sel]) {
            [anInvocation invokeWithTarget:p];
        }
        else {
            [self doesNotRecognizeSelector:sel];
        }
        
    }
    
    
    void foo(id obj,SEL _cmd){
        NSLog(@"VC foo");
    }

#import <Foundation/Foundation.h>
    
    NS_ASSUME_NONNULL_BEGIN
    
    @interface Preson : NSObject
    -(void)foo;
    @end
    
    NS_ASSUME_NONNULL_END

#import "Preson.h"
    
    @implementation Preson
    -(void)foo{
        NSLog(@"person foo");
    }
    @end