A extremely strange problem about UIScrollView

Lith · 08-31-2011, 06:11 AM

I just want to add a UIScrollView into my project, so I created a UIViewController class and added code below:

Code:

@interface TestScrollViewController : UIViewController<UIScrollViewDelegate> {
    IBOutlet UIScrollView *scrollView;
    UIImageView *imageView;
    
}
@property(nonatomic,retain)UIScrollView *scrollView;
@property(nonatomic,retain)UIImageView *imageView;

@end

and I added codes in the method of ViewDidLoad

Code:

- (void)viewDidLoad {
    [super viewDidLoad];
    
    UIImageView *tempImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"testScrollView.png"]];
    self.imageView = tempImageView;
    [tempImageView release];
    
    scrollView.contentSize = CGSizeMake(imageView.frame.size.width, imageView.frame.size.height);
    scrollView.maximumZoomScale = 4.0;
    scrollView.minimumZoomScale = 0.75;
    scrollView.clipsToBounds = YES;
    scrollView.delegate = self;
    scrollView.hidden = NO;
    scrollView.showsVerticalScrollIndicator = YES;
    [scrollView addSubview:imageView];
    self.view = scrollView;
 
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView{
    return imageView;
}

However it returns me just a blank screen, I also tried a lot of simple code about UIScrollView, but they don't work neither.

BTW I use the ViewController in a tabbar:

Code:

TestScrollViewController * vc2 = [[TestScrollViewController alloc] init];
 vc2.tabBarItem=[[UITabBarItem alloc] initWithTitle:@"Test" image:[UIImage imageNamed:@"my24.png"] tag:1];
/*
blablabla
*/
NSArray* controllers = [NSArray arrayWithObjects:nav1, vc2, nav3,vc4,nil];
myTabbarController.viewControllers = controllers;

Anyone could help?

dany_dev · 08-31-2011, 06:19 AM

Code:

    self.view = scrollView;

why?!

you should do

Code:

[self.view addSubView:scrollView];

And however you should alloc\init scrollview before do it. if you added the scrollview with IB, so you don't need to addSubView or change self.view

Lith · 08-31-2011, 07:38 AM

Quote:

Originally Posted by dany_dev

Code:

    self.view = scrollView;

why?!

you should do

Code:

[self.view addSubView:scrollView];

And however you should alloc\init scrollview before do it. if you added the scrollview with IB, so you don't need to addSubView or change self.view

Yes, I actually tried that before, I tried this code:

Code:

- (void)viewDidLoad {
    [super viewDidLoad];
    
    
    UIImageView *tempImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"testScrollView.png"]];
    self.imageView = tempImageView;
    [tempImageView release];
    
    scrollView = [[UIScrollView alloc]init];
    scrollView.contentSize = CGSizeMake(imageView.frame.size.width, imageView.frame.size.height);
    scrollView.maximumZoomScale = 4.0;
    scrollView.minimumZoomScale = 0.75;
    scrollView.clipsToBounds = YES;
    scrollView.delegate = self;
    scrollView.hidden = NO;
    scrollView.showsVerticalScrollIndicator = YES;
    [scrollView addSubview:imageView];
    [self.view addSubview:scrollView];
}
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView{
    return imageView;
}

but it turns out an infinite loop,that is the strange place.

Lith · 08-31-2011, 07:45 AM

Quote:

Originally Posted by dany_dev

Code:

    self.view = scrollView;

why?!

you should do

Code:

[self.view addSubView:scrollView];

And however you should alloc\init scrollview before do it. if you added the scrollview with IB, so you don't need to addSubView or change self.view

and also, it shows that this line [self.view addSubView:scrollView] cause the infinite loop.

Lith · 08-31-2011, 07:51 AM

Quote:

Originally Posted by Lith

and also, it shows that this line [self.view addSubView:scrollView] cause the infinite loop.

Ah!!!!!!!!
I finally solve the problem, the [self.view addSubView: scrollView] causes the problem, but the self.view = scrollView didn't, however, I really don't know why~

ThX all the same!!!

dany_dev · 08-31-2011, 08:58 AM

however it is an incorrect way to use UIViewController.

The problem maybe is generated by you modifying something in IB..

Lith · 08-31-2011, 08:41 PM

Quote:

Originally Posted by dany_dev

however it is an incorrect way to use UIViewController.

The problem maybe is generated by you modifying something in IB..

T^T,but, I didn't use nib file with this VC