objective-c - performSelector 的返回值 :

Question

performSelector 的返回值是什么:如果我传递一个返回原始类型(在对象上)的选择器，例如 NSDateComponents 上的 'week'(它将返回一个 int)？

Answer 1

使用 NSInvocation 返回 float 的示例:

SEL selector = NSSelectorFromString(@"someSelector");
if ([someInstance respondsToSelector:selector]) {
    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:
                                [[someInstance class] instanceMethodSignatureForSelector:selector]];
    [invocation setSelector:selector];
    [invocation setTarget:someInstance];
    [invocation invoke];
    float returnValue;
    [invocation getReturnValue:&returnValue];
    NSLog(@"Returned %f", returnValue);
}