performSelector支持多参数

默认的performSelector支持最多传递两个参数，要想传递超过两个的参数，需要使用NSInvocation来模拟performSelector的行为，如下：

- (id)performSelector:(SEL)aSelector withObjects:(NSArray *)argumentsArray

{

NSMethodSignature *sig = [selfmethodSignatureForSelector:aSelector];

if (sig)

{

NSInvocation *invocation = [NSInvocationinvocationWithMethodSignature:sig];

[invocation setTarget:self];

[invocation setSelector:aSelector];

for (int i = 0; i < argumentsArray.count ; ++i)

{

id argument = [argumentsArray objectAtIndex:i];

//此处+2不能漏

[invocation setArgument:&argument atIndex:i + 2];

}

[invocation invoke];

if (sig.methodReturnLength)

{

id anObject = nil;

[invocation getReturnValue:anObject];

return anObject;

}

return nil;

}

returnnil;

}