UIImage在开始时不适合UIScrollView

Question

我的图像如下：

当我将图像加载到uiimageview然后作为子视图添加到uiscrollview时，在开始时图像显示如下：

问题是我想在开始时看到所有图像都适合屏幕，但它显示已经缩放。有没有办法处理这个请帮助...

我的代码如下：

[self.view addSubview:scrollView];
UIImageView *tempImageView = 
[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Tree.jpg"]];
self.imageView = tempImageView;
[tempImageView release];
[scrollView setContentMode:UIViewContentModeScaleAspectFit];
[imageView sizeToFit];
scrollView.backgroundColor=[UIColor blackColor];
scrollView.contentSize = imageView.frame.size;
scrollView.minimumZoomScale = scrollView.frame.size.width / imageView.frame.size.width;
scrollView.maximumZoomScale = 4.0;
[scrollView setZoomScale:1.0];
scrollView.clipsToBounds = YES;
scrollView.delegate = self;
[scrollView addSubview:imageView];

Answer 1

可能你正在寻找这个，

UIImageView *tempImageView = [[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Watson.jpg"]] autorelease];
tempImageView.frame = scrollView.bounds;
self.imageView = tempImageView;

scrollView.backgroundColor = [UIColor blackColor];
scrollView.minimumZoomScale = 1.0  ;
scrollView.maximumZoomScale = imageView.image.size.width / scrollView.frame.size.width;
scrollView.zoomScale = 1.0;
scrollView.delegate = self;

[scrollView addSubview:imageView];

Answer 2

看一下UIView的contentMode-Property（UIImageView也支持这个）。

imageView.contentMode = UIViewContentModeScaleAspectFit;

这应该有用......

Answer 3

我认为问题在于

UIImageView *tempImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Tree.jpg"]];

Apple的文档称“此方法会调整接收器的帧以匹配指定图像的大小。默认情况下，它还会禁用图像视图的用户交互。”
改为使用

UIImageView *tempImageView = [[UIImageView alloc] initWithFrame:CGRectMake(0,0,320,480)];
tempImageView.image = [UIImage imageNamed:@"Tree.jpg"];

Answer 4

请注意，还有[scrollView zoomToRect：animated：]描述here

您可以将其设置为图像的外边界，以便在视图中自动调整图像。但请确保按照Deepak solution above正确设置maximumZoomScale。

Answer 5

我使用了Deepak的解决方案和Apples建议，并在其中使用UIImageView子类化了UIScrollView。但是，我只在我的scrollview子类的第一个布局上缩放图像，并且只有当帧大小小于图像大小时才会缩放图像：

- (void)layoutSubviews
{
[super layoutSubviews];

// center the image as it becomes smaller than the size of the screen
CGSize boundsSize = self.bounds.size;
CGRect frameToCenter = _imageView.frame;

// center horizontally
if (frameToCenter.size.width < boundsSize.width)
    frameToCenter.origin.x = (boundsSize.width - frameToCenter.size.width) / 2;
else
    frameToCenter.origin.x = 0;

// center vertically
if (frameToCenter.size.height < boundsSize.height)
    frameToCenter.origin.y = (boundsSize.height - frameToCenter.size.height) / 2;
else
    frameToCenter.origin.y = 0;

_imageView.frame = frameToCenter;

// If image is bigger than frame, we zoom it on first load (zoom value is smaller than 1.0)
if (_firstLayout) {
    _firstLayout = NO;
    self.zoomScale = (self.frame.size.width < _imageView.image.size.width) ? (self.frame.size.width / _imageView.image.size.width) : 1.0;
}
}

这是我初始化子类的方式：

- (id)initWithFrame:(CGRect)frame image:(UIImage*)image
{
self = [super initWithFrame:frame];
if (self) {

    _firstLayout = YES;

    _imageView = [[UIImageView alloc] initWithImage:image];
    [self addSubview:_imageView];

    self.backgroundColor = [UIColor blackColor];
    self.minimumZoomScale = 0.1;
    self.maximumZoomScale = 10;


    self.delegate = self;
}
return self;
}