我需要以模态方式调用ViewController,以在当前窗口的顶部显示一些UIButton和其他UIView。我希望背景部分透明并显示其下方的当前窗口 - 类似于UIActionSheet但具有自定义设计。我编写了VC来执行以下操作:1)在初始化期间,VC将self.view.frame设置为[[UIApplication sharedApplication] keyWindow] .frame 2)当调用show()时,VC将self.view添加到[ [UIApplication sharedApplication] keyWindow] subViews 3)当内部按钮调用私有方法release()时,VC从其superview中删除self.view。使用单个释放按钮的示例如下:
@implementation ModalController
- (id)init
{
self = [super init];
if (self){
//set my view frame equal to the keyWindow frame
self.view.frame = [[UIApplication sharedApplication]keyWindow].frame;
self.view.backgroundColor = [UIColor colorWithWhite:0.3f alpha:0.5f];
//create a button to release the current VC with the size of the entire view
UIButton *releaseMyselfButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[releaseMyselfButton setTitle:@"Release" forState:UIControlStateNormal];
releaseMyselfButton.frame = CGRectMake(0, 0, 90, 20);
[releaseMyselfButton addTarget:self action:@selector(releaseMyself) forControlEvents:UIControlEventTouchDown];
//add the button to the view
[self.view addSubview:releaseMyself];
}
return self;
}
- (void) show
{
//add self.view to the keyWindow to make sure that it will appear on top of everything else
[[[UIApplication sharedApplication]keyWindow] addSubview:self.view];
}
- (void)releaseMyself
{
[self.view removeFromSuperview];
}
@end
如果我从另一个VC创建一个ModalController实例,我调用show(),一切都按预期进行:
@interface CurrentVC ()
@property (strong, nonatomic) ModalController *myModalController;
@end
@implementation CurrentVC
- (void)viewDidLoad
{
[super viewDidLoad];
self.myModalController = [[ModalController alloc]init];
[self.myModalController show];
}
@end
为了使它工作,我需要在属性中保留ModalController,直到调用release()。但是我想拥有与UIActionSheet相同的自由,只需将它的实例保存在局部变量中:
@implementation CurrentVC
- (void)viewDidLoad
{
[super viewDidLoad];
ModalController *myModalController = [[ModalController alloc]init];
[myModalController show];
}
@end
如果我使用当前代码执行此操作,ARC将在调用show()之后直接释放myModalController,并且释放按钮将指向nil。如何在不将对象存储在属性中的情况下完成此工作?我已经找到了解决方法,但我不确定这是一个很好的设计选择:
@interface ModalController ()
@property (strong, nonatomic) ModalController *myselfToAutorelease;
@implementation ModalController
- (id)init
{
self = [super init];
if (self){
... ... ...
self.myselfToAutorelease = self;
}
return self;
}
- (void) show
{
... ... ...
}
- (void)releaseMyself
{
[self.view removeFromSuperview];
self.myselfToAutorelease = nil;
}
我所做的是让ModalController“自给自足” - 它在init期间存储一个指向自身的指针,并在它准备释放自己时将其设置为nil。它有效,但我觉得这违反了ARC的设计原则!这种方法是否正确?如果没有,我该如何区别对待?
提前感谢您的帮助。
答案 0 :(得分:0)
不能那样工作。 你没有提到自我。 在主视图控制器中,您只需创建对象。如果需要将其保存在较长时间,请将其保存在主视图控制器的属性中,完成后,在主视图控制器中将该属性设置为nil。