使用NSInvocation的UIButton

Question

我试图以一种编程的方式添加一个按钮，当按下它时，某个对象就会被传递。我一直收到“未识别的选择器已发送”异常。你能建议一下代码有什么问题吗：

    // allocate the details button's action
    SEL selector = @selector(showPropertyDetails:forProperty:);
    NSMethodSignature *signature = [[self class] instanceMethodSignatureForSelector:selector];
    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
    [invocation setSelector:selector];
    //The invocation object must retain its arguments
    [property retain];      
    //Set the arguments
    [invocation setTarget:self];
    [invocation setArgument:&property atIndex:3];       
    [(UIButton*)[myView viewWithTag:15] addTarget:self action:@selector(selector) forControlEvents:UIControlEventTouchDown];

再往下看，同一个类中的方法如下所示：

-(void) showPropertyDetails:(id)something forProperty:(Property *)property {
int i=0;
}

Answer 1

在构建NSInvocation时，您不会在任何地方使用它-您只是将selector设置为按钮的action。此选择器应具有类似于- (void)foo:(id)sender, ...的形式。

相反，您可以使用字典，例如，将标签用作映射到某个NSInvocation或存储其他参数的键。

Answer 2

我用一种不同的方式解决了它。继承了UIButton，并添加了我需要的所有属性。这是这个类的样子：

@interface RecentSalePropertyDetailsButton : UIButton {
    Property* property;
}
@property (nonatomic, retain) Property* property;
@end
@implementation RecentSalePropertyDetailsButton
@synthesize property;
- (id) initWithPropertyAs:(Property*)aProperty{
    [super init];
    self.property = aProperty;
    return self;
}
@end

然后，再往下看，我执行以下操作：

    // allocate the details button's action
    RecentSalePropertyDetailsButton* button = (RecentSalePropertyDetailsButton *)[myView viewWithTag:15];
    button.property = property;
    [button addTarget:self action:@selector(showRecentSalesPropertyDetails:) forControlEvents:UIControlEventTouchDown];

Answer 3

//make a button
    UIButton *button = [UIButton buttonWithType:0];
//set button size
    button.frame = CGRectMake(20,219,280,106);
//give it a color
    button.backgroundColor = [UIColor clearColor];
//add a method
    [button addTarget:self action:@selector(cancel) forControlEvents:UIControlEventTouchUpInside];
//add it to the currentview 
    [self.view addSubview:button];