UIImageView无法正确更新边界

Question

I am currently trying to program a game with a HP gauge represented by an UIImageView placed on a .xib file. I declared my IBOutlet as follows:

@property (weak, nonatomic) IBOutlet UIImageView *hpGaugeView;

and synthesized accordingly. It is also linked to the UIImageView instance in the xib.

In the xib, I set the length of hpGaugeView to 188 and height to 9.

Now this is what I did in viewDidLoad:

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.

    [hpGaugeView setFrame:CGRectMake(49, 18, 123, 9)];
    NSLog(@"%f, %f", [hpGaugeView frame].size.width, [hpGaugeView frame].size.height);
}

Although NSLog tells me the hpGaugeView's width is 123, when I run it the length appears unchanged compared to the one in xib. All the other setFrame: or setBound: worked fine in other viewControllers, so I'm just wondering what's happening here.

It is a small but crucial problem that is bugging me for a few hours straight...

Edit: When I turn off AutoLayout, the resizing worked; it creates a bunch of other problems though...

Answer 1

With autolayout on, the subviews have not been laid during the viewDidLoad. The constraints are calculated a bit later and you can override the viewDidLayoutSubviews method to set your frame:

- (void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];

    // Do any additional setup after subviews are laid.
    [hpGaugeView setFrame:CGRectMake(49, 18, 123, 9)];
    NSLog(@"%f, %f", [hpGaugeView frame].size.width, [hpGaugeView frame].size.height);
}

From the class reference:

viewDidLayoutSubviews

Notifies the view controller that its view just laid out its subviews.

Answer 2

I believe the problem is that you're not changing the frame of the UIImageView . The bounds refer to the position and size of the view in it's own coordinate system whereas the frame refers to the position and size in it's superview coordinate system. If the clipsToBounds property is set yo YES, then nothing outside the frame of your view will be visible.

Answer 3

事实证明，笔尖和代码之间存在一些怪异的怪异相互作用……当我以编程方式创建UIImageView时，它运行良好。

Answer 4

AutoLayout property worked only above IOS 6.0 only . Dragging of control to XIB instead of you can create the UIImageView through Code and add to current view. I have given the code for adding UIImageView programmatically.

Source Code:

// .h file
@property (weak, nonatomic) UIImageView *hpGaugeView;

//.m file
- (void)viewDidLoad
{
    [super viewDidLoad];

    hpGaugeView = [[UIImageView alloc] init];

    [hpGaugeView setFrame:CGRectMake(49, 18, 123, 9)];

    [self.view addSubview:hpGaugeView];

}

Initialize and add the hpGaugeView to subview inside the viewDidLoad function through programmatically.