将子视图添加到选择器中的主要uiview中

Question

我正在处理拖放应用程序，当用户拖放图像时，我想从拖动点中复制它，然后原始图像返回到初始点。 我决定执行touchesEnded后的UIImageView添加到我的ViewController，

我有一个包含该方法拖动视图类：

- (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event 
{ 

CGPoint activePoint = [[touches anyObject] locationInView:self]; 
UIImageView *myimage; 
myimage.image = self.image; 
myimage.center = activePoint; 


ViewController *cview ; 
cview = [[ViewController alloc]init]; 
[cview getpoint: myimage]; 

} 

现在，在视图控制器，这是用GetPoint选择器：

-(void) getpoint : (UIImageView *) mine{ 
UIImageView *newimage; 
newimage = mine; 
[self.view addSubview:newimage]; 


NSLog(@" in getpoint"); 

} 

当我放弃物体时，出现此错误：

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSArrayM insertObject:atIndex:]: object cannot be nil' 

但是当我删除addsubview语句时，NSlog正在向右

任何解决方案？

Answer 1

你实际上并没有为你的UIImageViews分配内存。此代码是犯罪嫌疑人：

CGPoint activePoint = [[touches anyObject] locationInView:self]; 
UIImageView *myimage; 
myimage.image = self.image; 
myimage.center = activePoint; 

您需要分配/初始化您的图像视图

CGPoint activePoint = [[touches anyObject] locationInView:self]; 
UIImageView *myimage = [[UIImageView alloc] initWithFrame:rect]; 
myimage.image = self.image; 
myimage.center = activePoint; 

其中rect变量包含你想添加到层级图像视图的矩形尺寸。您不能将一个零对象添加到NSArray。因此，由于是UIImageView的零，此调用将会失败：

[self.view addSubview:newimage];