iOS方法调用总结

1.直接调用

- (void)callFunc1 {
    ViewController *someObj = [ViewController new];
    [someObj foo:@"1"];
}

2.performSelector

- (void)callFunc2 {
    ViewController *someObj = [ViewController new];
    [someObj performSelector:@selector(foo:) withObject:@"2"];
}

3. NSInvocation

- (void)callFunc3 {
    ViewController *someObj = [ViewController new];
    //获取方法签名
    NSMethodSignature *signature = [self methodSignatureForSelector:@selector(foo:)];
    //获取方法签名对应的invocation
    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
    //设置消息接受者，与[invocation setArgument:(__bridge void * _Nonnull)(self) atIndex:0]等价
    [invocation setTarget:someObj];
    //设置要执行的selector。与[invocation setArgument:@selector(foo:) atIndex:1] 等价
    [invocation setSelector:@selector(foo:)];
    //设置参数
    NSString *str = @"3";
    [invocation setArgument:&str atIndex:2];
    //开始执行
    [invocation invoke];
}

4. NSInvocationOperation

- (void)callFunc4 {
    ViewController *someObj = [ViewController new];
    NSInvocationOperation *invocationOp = [[NSInvocationOperation alloc] initWithTarget:someObj selector:@selector(foo:) object:nil];
    NSString *str = @"4";
    [invocationOp.invocation setArgument:&str atIndex:2];
    [invocationOp start];
//    NSInteger ret = 0;
//    [invocationOp.result getValue:&ret]; //获取返回值要调用这个方法
}

5.objc_msgSend函数指针

- (void)callFunc5 {
    ViewController *someObj = [ViewController new];
    SEL selector = NSSelectorFromString(@"foo:");
    IMP imp = [someObj methodForSelector:selector];
    void (*msgSendPointer)(id, SEL, NSString*) = (void *)imp;
    msgSendPointer(someObj, selector, @"5");
}

ViewController的foo方法

- (void)foo:(NSString*)value {
    NSArray *syms = [NSThread  callStackSymbols];
    if ([syms count] > 1) {
        NSLog(@"foo=%@=== %@ ", value,[syms objectAtIndex:1]);
    }
}