只知道类名 动态调用方法

   Class cls = NSClassFromString(@"a");
    
    [cls performSelector:NSSelectorFromString(@"show")];
    
    Method method = class_getInstanceMethod(cls, NSSelectorFromString(@"run"));
    if (method) {
        IMP imp = method_getImplementation(method);
        imp();
    }

- (id)performSelector:(SEL)aSelector onTarget:(id)target withArgs:(NSArray *)args
{
    id ret = nil;
    
    if (aSelector == nil || target == nil || ![target respondsToSelector:aSelector]) {
        return ret;
    }
    
    NSLog(@"【action】%@ %@ %@ %@",NSStringFromSelector(_cmd),NSStringFromClass([target class]),NSStringFromSelector(aSelector),args);
    NSMethodSignature *signature = [target methodSignatureForSelector:aSelector];
    if (args.count + 2 != signature.numberOfArguments) {
        return ret;
    }
    
    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
    [invocation setSelector:aSelector];
    [invocation setTarget:target];
    for (int i = 2, j = 0; j < args.count; i++, j++) {
        id arg = [args objectAtIndex:j];
        [invocation setArgument:&arg atIndex:i];
    }
    [invocation invoke];
    
    NSUInteger length = [[invocation methodSignature] methodReturnLength];
    //    void *buffer = (void *)malloc(length);
    if (length > 0) {
        [invocation getReturnValue:&ret];
    }
    
    return ret;
}

- (id)performClassSelector:(SEL)aSelector onTarget:(Class)target withArgs:(NSArray *)args
{
    id ret = nil;
    
    NSLog(@"【action】%@ %@ %@ %@",NSStringFromSelector(_cmd),NSStringFromClass([target class]),NSStringFromSelector(aSelector),args);
    if (aSelector == nil || target == nil) {
        return ret;
    }
    
    NSMethodSignature *signature = [target methodSignatureForSelector:aSelector];
    if (args.count + 2 != signature.numberOfArguments) {
        return ret;
    }
    
    NSMutableString *argsInCTypes = [NSMutableString stringWithString:@"v"];
    for (int i = 0; i < args.count; ++i) {
        [argsInCTypes appendString:@"@:"];
    }
    signature = [target methodSignatureForSelector:aSelector]; // [NSMethodSignature signatureWithObjCTypes:argsInCTypes.UTF8String];
    if (signature == nil) {
        return ret;
    }
    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
    [invocation setSelector:aSelector];
    [invocation setTarget:target];
    for (int i = 2, j = 0; j < args.count; i++, j++) {
        id arg = [args objectAtIndex:j];
        [invocation setArgument:&arg atIndex:i];
    }
    [invocation invoke];
    
    NSUInteger length = [[invocation methodSignature] methodReturnLength];
    //    void *buffer = (void *)malloc(length);
    if (length > 0) {
        [invocation getReturnValue:&ret];
    }
    
    return ret;
}