对于我的UIImageView我选择了Aspect Fit（InterfaceBuilder），但是如何更改垂直对齐？
[编辑 - 此代码从2011年开始有点发霉，除了我合并@ ArtOfWarefare的mods]
你不能用UIImageView这样做。我创建了一个包含UIImageView的简单UIView子类MyImageView。代码如下。
// MyImageView.h
#import <UIKit/UIKit.h>
@interface MyImageView : UIView {
UIImageView *_imageView;
}
@property (nonatomic, assign) UIImage *image;
@end
和
// MyImageView.m
#import "MyImageView.h"
@implementation MyImageView
@dynamic image;
- (id)initWithCoder:(NSCoder*)coder
{
self = [super initWithCoder:coder];
if (self) {
self.clipsToBounds = YES;
_imageView = [[UIImageView alloc] initWithFrame:self.bounds];
_imageView.contentMode = UIViewContentModeScaleAspectFill;
[self addSubview:_imageView];
}
return self;
}
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
self.clipsToBounds = YES;
_imageView = [[UIImageView alloc] initWithFrame:self.bounds];
_imageView.contentMode = UIViewContentModeScaleAspectFill;
[self addSubview:_imageView];
}
return self;
}
- (id)initWithImage:(UIImage *)anImage
{
self = [self initWithFrame:CGRectZero];
if (self) {
_imageView.image = anImage;
[_imageView sizeToFit];
// initialize frame to be same size as imageView
self.frame = _imageView.bounds;
}
return self;
}
// Delete this function if you're using ARC
- (void)dealloc
{
[_imageView release];
[super dealloc];
}
- (UIImage *)image
{
return _imageView.image;
}
- (void)setImage:(UIImage *)anImage
{
_imageView.image = anImage;
[self setNeedsLayout];
}
- (void)layoutSubviews
{
if (!self.image) return;
// compute scale factor for imageView
CGFloat widthScaleFactor = CGRectGetWidth(self.bounds) / self.image.size.width;
CGFloat heightScaleFactor = CGRectGetHeight(self.bounds) / self.image.size.height;
CGFloat imageViewXOrigin = 0;
CGFloat imageViewYOrigin = 0;
CGFloat imageViewWidth;
CGFloat imageViewHeight;
// if image is narrow and tall, scale to width and align vertically to the top
if (widthScaleFactor > heightScaleFactor) {
imageViewWidth = self.image.size.width * widthScaleFactor;
imageViewHeight = self.image.size.height * widthScaleFactor;
}
// else if image is wide and short, scale to height and align horizontally centered
else {
imageViewWidth = self.image.size.width * heightScaleFactor;
imageViewHeight = self.image.size.height * heightScaleFactor;
imageViewXOrigin = - (imageViewWidth - CGRectGetWidth(self.bounds))/2;
}
_imageView.frame = CGRectMake(imageViewXOrigin,
imageViewYOrigin,
imageViewWidth,
imageViewHeight);
}
- (void)setFrame:(CGRect)frame
{
[super setFrame:frame];
[self setNeedsLayout];
}
@end
如果你需要实现aspectFit并摆脱空白空间
别忘了从故事板中删除imageview的宽度约束并享受
class SelfSizedImageView：UIImageView {
override func layoutSubviews() {
super.layoutSubviews()
guard let imageSize = image?.size else {
return
}
let viewBounds = bounds
let imageFactor = imageSize.width / imageSize.height
let newWidth = viewBounds.height * imageFactor
let myWidthConstraint = self.constraints.first(where: { $0.firstAttribute == .width })
myWidthConstraint?.constant = min(newWidth, UIScreen.main.bounds.width / 3)
layoutIfNeeded()
}}
要对齐缩放比例图像，请使用自动布局。在UIImageView中按比例缩放后右对齐图像的示例：
myUIImageView.contentMode = .ScaleAspectFit myUIImageView.translatesAutoresizingMaskIntoConstraints = false myUIImageView.image = UIImage(named:"pizza.png")
您的方面适合缩放图像现在在UIImageView中右对齐
+----------------------------------+
| [IMAGE]|
+----------------------------------+
更改约束以在imageview中以不同方式对齐。
如果使用Storyboard，这可以通过约束来实现......
首先是具有所需最终帧/约束的UIView。将UIImageView添加到UIView。将contentMode设置为Aspect Fill。使UIImageView框架与图像的比例相同（这可以避免以后的任何Storyboard警告）。使用标准约束将边固定到UIView。使用标准约束将顶部或底部（取决于您想要对齐的位置）固定到UIView。最后将一个宽高比约束添加到UIImageView（确保比率作为图像）。
这有点棘手，因为如果您已经选择了内容模式（.scaleAspectFit），则无法设置更多对齐规则。
但这是一个解决方法：
首先需要通过计算尺寸明确地调整源图像的大小（如果它与UIImageView在contentMode = .scaleAspectFit中）。
extension UIImage {
func aspectFitImage(inRect rect: CGRect) -> UIImage? {
let width = self.size.width
let height = self.size.height
let aspectWidth = rect.width / width
let aspectHeight = rect.height / height
let scaleFactor = aspectWidth > aspectHeight ? rect.size.height / height : rect.size.width / width
UIGraphicsBeginImageContextWithOptions(CGSize(width: width * scaleFactor, height: height * scaleFactor), false, 0.0)
self.draw(in: CGRect(x: 0.0, y: 0.0, width: width * scaleFactor, height: height * scaleFactor))
defer {
UIGraphicsEndImageContext()
}
return UIGraphicsGetImageFromCurrentImageContext()
}
}
然后，您只需要通过传递imageView的框架并将结果分配给UIImageView.image属性，就可以在原始图像上调用此函数。此外，请确保在此处（甚至在界面生成器中）设置imageView所需的contentMode！
let image = UIImage(named: "MySourceImage")
imageView.image = image?.aspectFitImage(inRect: imageView.frame)
imageView.contentMode = .left
尝试设置：
imageView.contentMode = UIViewContentModeScaleAspectFit;
imageView.clipsToBounds = YES;
这对我有用。
由于开发人员的缘故，我使用了UIImageViewAligned来改变图像的对齐方式
我知道这是一个老线程，但我想我会分享我在Interface Builder中从图像视图的顶部到底部轻松更改剪切区域，以防万一我遇到同样的问题。我有一个UIImageView填充了我的ViewController视图，并试图使顶部保持不变，与设备屏幕的大小无关。
现在，当屏幕改变大小时，UIImageView实际上是相同的大小，视图控制器只是剪辑屏幕外的内容。帧原点保持为0,0，因此图像的底部和右侧被剪裁，而不是顶部。
希望这可以帮助。
您可以通过首先缩放然后调整大小来完成。这里要提到的是我受到身高的限制。我的意思是，我必须有34px高的图像，无论宽度如何。
因此，获取实际内容高度与视图高度之间的比率（34像素），然后也缩放宽度。
我是这样做的：
CGSize size = [imageView sizeThatFits:imageView.frame.size];
CGSize actualSize;
actualSize.height = imageView.frame.size.height;
actualSize.width = size.width / (1.0 * (size.height / imageView.frame.size.height));
CGRect frame = imageView.frame;
frame.size = actualSize;
[imageView setFrame:frame];
希望这可以帮助。
我找到了以下解决方案：
UIImageView内容模式设置为top：imageView.contentMode = .top要加载和调整图像大小我使用Kingfisher：
let size = imageView.bounds.size
let processor = ResizingImageProcessor(referenceSize: size, mode: .aspectFit)
imageView.kf.setImage(with: URL(string: imageUrl), options: [.processor(processor)])
我通过继承UIImageView并重写setImage：方法解决了这个问题。子类首先存储它的原始值和大小的原始值，以便它可以使用原始集大小作为边界框。
我将内容模式设置为UIViewContentModeAspectFit。在setImage里面：我抓住图像的宽高比，然后调整图像视图的大小以适应与图像相同的比例。调整大小后，我调整了我的帧属性，将图像视图设置在之前的相同位置，然后我调用了超级setImage：。
这导致图像视图的框架被调整为精确地适合图像，因此纵横比适合工作，并且图像视图框架属性正在进行繁重的工作，将图像视图放在应该达到相同效果的位置。
这是我使用的一些代码：
首先，我发现它一般非常有用，是UIView上的一个类别，可以通过左，右，顶部，底部，宽度，高度等属性轻松设置视图的框架属性。
@interface UIView (FrameAdditions)
@property CGFloat left, right, top, bottom, width, height;
@property CGPoint origin;
@end
@implementation UIView (FrameAdditions)
- (CGFloat)left {
return self.frame.origin.x;
}
- (void)setLeft:(CGFloat)left {
self.frame = CGRectMake(left, self.frame.origin.y, self.frame.size.width, self.frame.size.height);
}
- (CGFloat)right {
return self.frame.origin.x + self.frame.size.width;
}
- (void)setRight:(CGFloat)right {
self.frame = CGRectMake(right - self.frame.size.width, self.frame.origin.y, self.frame.size.width, self.frame.size.height);
}
- (CGFloat)top {
return self.frame.origin.y;
}
- (void)setTop:(CGFloat)top {
self.frame = CGRectMake(self.frame.origin.x, top, self.frame.size.width, self.frame.size.height);
}
- (CGFloat)bottom {
return self.frame.origin.y + self.frame.size.height;
}
- (void)setBottom:(CGFloat)bottom {
self.frame = CGRectMake(self.frame.origin.x, bottom - self.frame.size.height, self.frame.size.width, self.frame.size.height);
}
- (CGFloat)width {
return self.frame.size.width;
}
- (void)setWidth:(CGFloat)width {
self.frame = CGRectMake(self.frame.origin.x, self.frame.origin.y, width, self.frame.size.height);
}
- (CGFloat)height {
return self.frame.size.height;
}
- (void)setHeight:(CGFloat)height {
self.frame = CGRectMake(self.frame.origin.x, self.frame.origin.y, self.frame.size.width, height);
}
- (CGPoint)origin {
return self.frame.origin;
}
- (void)setOrigin:(CGPoint)origin {
self.frame = CGRectMake(origin.x, origin.y, self.frame.size.width, self.frame.size.height);
}
@end
这是UIImageView的子类。它没有经过全面测试，但应该了解这个想法。这可以扩展为设置自己的新对齐模式。
@interface BottomCenteredImageView : UIImageView
@end
@interface BottomCenteredImageView() {
CGFloat originalLeft;
CGFloat originalBottom;
CGFloat originalHeight;
CGFloat originalWidth;
}
@end
@implementation BottomCenteredImageView
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if(self) {
[self initialize];
}
return self;
}
- (void)awakeFromNib {
[self initialize];
}
- (void)initialize {
originalLeft = self.frame.origin.x;
originalHeight = CGRectGetHeight(self.frame);
originalWidth = CGRectGetWidth(self.frame);
originalBottom = self.frame.origin.y + originalHeight;
}
- (void)setImage:(UIImage *)image {
if(image) {
self.width = originalWidth;
self.height = originalHeight;
self.left = originalLeft;
self.bottom = originalBottom;
float myWidthToHeightRatio = originalWidth/originalHeight;
float imageWidthToHeightRatio = image.size.width/image.size.height;
if(myWidthToHeightRatio >= imageWidthToHeightRatio) {
// Calculate my new width
CGFloat newWidth = self.height * imageWidthToHeightRatio;
self.width = newWidth;
self.left = originalLeft + (originalWidth - self.width)/2;
self.bottom = originalBottom;
} else {
// Calculate my new height
CGFloat newHeight = self.width / imageWidthToHeightRatio;
self.height = newHeight;
self.bottom = originalBottom;
}
self.contentMode = UIViewContentModeScaleAspectFit;
[super setImage:image];
} else {
[super setImage:image];
}
}
@end