我正在开发一个应用程序。我正在使用imageviews。在更改UIImageview图像之前，我需要在UIimage obejct中拍摄该图像并与另一个{{1}进行比较用于查找两者的对象是否为sam。所以请告诉我如何做到这一点。
答案 0 :(得分：117)
一种方法是首先将它们转换为图像数据，然后进行比较。
- (BOOL)image:(UIImage *)image1 isEqualTo:(UIImage *)image2
{
NSData *data1 = UIImagePNGRepresentation(image1);
NSData *data2 = UIImagePNGRepresentation(image2);
return [data1 isEqual:data2];
}
答案 1 :(得分：20)
Swift实现@ Simon的回答：
func image(image1: UIImage, isEqualTo image2: UIImage) -> Bool {
let data1: NSData = UIImagePNGRepresentation(image1)!
let data2: NSData = UIImagePNGRepresentation(image2)!
return data1.isEqual(data2)
}
或者根据@nhgrif的建议扩展UIImage：
import UIKit
extension UIImage {
func isEqualToImage(image: UIImage) -> Bool {
let data1: NSData = UIImagePNGRepresentation(self)!
let data2: NSData = UIImagePNGRepresentation(image)!
return data1.isEqual(data2)
}
}
答案 2 :(得分：8)
当两者都使用[UIImage imageNamed:]时，我们可以使用isEqual:，否则我们可以比较数据。
答案 3 :(得分：6)
正确的答案取决于“你想做什么样的比较？”。
但是你可以在facebook的ios-snapshot-test-case项目上查看好的例子：link right to the needed file。 您可以使用性能测试来测量处理时间。
对于伟大的正义，我将从下面复制代码：
- (BOOL)fb_compareWithImage:(UIImage *)image tolerance:(CGFloat)tolerance
{
NSAssert(CGSizeEqualToSize(self.size, image.size), @"Images must be same size.");
CGSize referenceImageSize = CGSizeMake(CGImageGetWidth(self.CGImage), CGImageGetHeight(self.CGImage));
CGSize imageSize = CGSizeMake(CGImageGetWidth(image.CGImage), CGImageGetHeight(image.CGImage));
// The images have the equal size, so we could use the smallest amount of bytes because of byte padding
size_t minBytesPerRow = MIN(CGImageGetBytesPerRow(self.CGImage), CGImageGetBytesPerRow(image.CGImage));
size_t referenceImageSizeBytes = referenceImageSize.height * minBytesPerRow;
void *referenceImagePixels = calloc(1, referenceImageSizeBytes);
void *imagePixels = calloc(1, referenceImageSizeBytes);
if (!referenceImagePixels || !imagePixels) {
free(referenceImagePixels);
free(imagePixels);
return NO;
}
CGContextRef referenceImageContext = CGBitmapContextCreate(referenceImagePixels,
referenceImageSize.width,
referenceImageSize.height,
CGImageGetBitsPerComponent(self.CGImage),
minBytesPerRow,
CGImageGetColorSpace(self.CGImage),
(CGBitmapInfo)kCGImageAlphaPremultipliedLast
);
CGContextRef imageContext = CGBitmapContextCreate(imagePixels,
imageSize.width,
imageSize.height,
CGImageGetBitsPerComponent(image.CGImage),
minBytesPerRow,
CGImageGetColorSpace(image.CGImage),
(CGBitmapInfo)kCGImageAlphaPremultipliedLast
);
if (!referenceImageContext || !imageContext) {
CGContextRelease(referenceImageContext);
CGContextRelease(imageContext);
free(referenceImagePixels);
free(imagePixels);
return NO;
}
CGContextDrawImage(referenceImageContext, CGRectMake(0, 0, referenceImageSize.width, referenceImageSize.height), self.CGImage);
CGContextDrawImage(imageContext, CGRectMake(0, 0, imageSize.width, imageSize.height), image.CGImage);
CGContextRelease(referenceImageContext);
CGContextRelease(imageContext);
BOOL imageEqual = YES;
// Do a fast compare if we can
if (tolerance == 0) {
imageEqual = (memcmp(referenceImagePixels, imagePixels, referenceImageSizeBytes) == 0);
} else {
// Go through each pixel in turn and see if it is different
const NSInteger pixelCount = referenceImageSize.width * referenceImageSize.height;
FBComparePixel *p1 = referenceImagePixels;
FBComparePixel *p2 = imagePixels;
NSInteger numDiffPixels = 0;
for (int n = 0; n < pixelCount; ++n) {
// If this pixel is different, increment the pixel diff count and see
// if we have hit our limit.
if (p1->raw != p2->raw) {
numDiffPixels ++;
CGFloat percent = (CGFloat)numDiffPixels / pixelCount;
if (percent > tolerance) {
imageEqual = NO;
break;
}
}
p1++;
p2++;
}
}
free(referenceImagePixels);
free(imagePixels);
return imageEqual;
}
答案 4 :(得分：5)
将图像转换为JPG / PNG，或依赖可访问性标识符要么是昂贵的操作，要么是脆弱的＆amp;容易失败。
在此，我遵循Apple在following link：
提供的建议isEqual（ :)方法是唯一可靠的方法来确定是否 两个图像包含相同的图像数据。您创建的图像对象 即使用它们初始化它们也可能彼此不同 相同的缓存图像数据。确定其平等的唯一方法 是使用isEqual（ :)方法，它比较实际图像 数据。清单1说明了正确和错误的比较方法 图像。
为简化起见，我创建了以下扩展来进行比较，这样我就可以避免转换第一张图片的问题：
add_action('genesis_after_content_sidebar_wrap', 'add_undergrad_Highlight', 1);
function add_undergrad_Highlight(){
global $post;
global $meta;
echo'<div id="highlightBox">';
if(isset($meta['HighlightImage'])){
$HighlightImage = '<img src="';
$HighlightImage .= $meta['HighlightImage'];
$HighlightImage .= '"/>';
}
if(isset($meta['HighlightImage'])){
echo $HighlightImage;
}
echo'</div>';
有了这个，我现在可以设置一个例子来比较一对图像：
import UIKit
extension UIImage {
func isEqual(to image: UIImage) -> Bool {
return isEqual(image)
}
}
答案 5 :(得分：5)
我对Mark的答案进行了一些更改，并使用了Data和elementsEqual而不是NSData和isEqual。
extension UIImage {
func isEqual(to image: UIImage) -> Bool {
guard let data1: Data = UIImagePNGRepresentation(self),
let data2: Data = UIImagePNGRepresentation(image) else {
return false
}
return data1.elementsEqual(data2)
}
}
答案 6 :(得分：4)
我的首选（Swift）解决方案
import UIKit
func ==(lhs: UIImage, rhs: UIImage) -> Bool
{
guard let data1 = UIImagePNGRepresentation(lhs),
data2 = UIImagePNGRepresentation(rhs)
else { return false }
return data1.isEqual(data2)
}
答案 7 :(得分：4)
Swift 3
有两种方法。如： -
1）使用isEqual（）函数。
self.image?.isEqual(UIImage(named: "add-image"))
2）使用accessibilityIdentifier
将accessibilityIdentifier设置为图像名称
myImageView.image?.accessibilityIdentifier = "add-image"
然后使用以下代码。
extension UIImageView
{
func getFileName() -> String? {
// First set accessibilityIdentifier of image before calling.
let imgName = self.image?.accessibilityIdentifier
return imgName
}
}
最后，识别方法的调用方式
myImageView.getFileName()
答案 8 :(得分：3)
将Mark Tickner的解决方案更新为Swift 4
import UIKit
extension UIImage {
func isEqualToImage(image: UIImage) -> Bool {
let data1 = self.pngData()
let data2 = image.pngData()
return data1 == data2
}
}
这两个变量可能是过大的，但它们可能有助于向新手解释。可以缩短为：
import UIKit
extension UIImage {
func isEqualToImage(image: UIImage) -> Bool {
return self.pngData() == image.pngData()
}
}
答案 9 :(得分：2)
对于较便宜的方法，最初比较图像大小。即使图像内部发生微小变化，尺寸也会不同。
NSData *data1 = UIImagePNGRepresentation(image1);
NSData *data2 = UIImagePNGRepresentation(image2);
if(data1.length == data2.length) {
// if required, compare the data to confirm it
if(data1 isEqual:data2) {
// images are exactly same
} else {
// even though size is same images are different
}
} else {
// images are different.
}
在比较来自相同来源（相同尺寸，格式等）的图像时成功进行了测试。
答案 10 :(得分：1)
这种方法效果很好：
func isEqualImages(image1: UIImage, image2: UIImage) -> Bool {
let data1: Data? = UIImagePNGRepresentation(image1)
let data2: Data? = UIImagePNGRepresentation(image2)
return data1 == data2
}
答案 11 :(得分：1)
Swift 4.x版本的Facebook比较算法：
/// Value in range 0...100 %
typealias Percentage = Float
// See: https://github.com/facebookarchive/ios-snapshot-test-case/blob/master/FBSnapshotTestCase/Categories/UIImage%2BCompare.m
private func compare(tolerance: Percentage, expected: Data, observed: Data) throws -> Bool {
guard let expectedUIImage = UIImage(data: expected), let observedUIImage = UIImage(data: observed) else {
throw Error.unableToGetUIImageFromData
}
guard let expectedCGImage = expectedUIImage.cgImage, let observedCGImage = observedUIImage.cgImage else {
throw Error.unableToGetCGImageFromData
}
guard let expectedColorSpace = expectedCGImage.colorSpace, let observedColorSpace = observedCGImage.colorSpace else {
throw Error.unableToGetColorSpaceFromCGImage
}
if expectedCGImage.width != observedCGImage.width || expectedCGImage.height != observedCGImage.height {
throw Error.imagesHasDifferentSizes
}
let imageSize = CGSize(width: expectedCGImage.width, height: expectedCGImage.height)
let numberOfPixels = Int(imageSize.width * imageSize.height)
// Checking that our `UInt32` buffer has same number of bytes as image has.
let bytesPerRow = min(expectedCGImage.bytesPerRow, observedCGImage.bytesPerRow)
assert(MemoryLayout<UInt32>.stride == bytesPerRow / Int(imageSize.width))
let expectedPixels = UnsafeMutablePointer<UInt32>.allocate(capacity: numberOfPixels)
let observedPixels = UnsafeMutablePointer<UInt32>.allocate(capacity: numberOfPixels)
let expectedPixelsRaw = UnsafeMutableRawPointer(expectedPixels)
let observedPixelsRaw = UnsafeMutableRawPointer(observedPixels)
let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedLast.rawValue)
guard let expectedContext = CGContext(data: expectedPixelsRaw, width: Int(imageSize.width), height: Int(imageSize.height),
bitsPerComponent: expectedCGImage.bitsPerComponent, bytesPerRow: bytesPerRow,
space: expectedColorSpace, bitmapInfo: bitmapInfo.rawValue) else {
expectedPixels.deallocate()
observedPixels.deallocate()
throw Error.unableToInitializeContext
}
guard let observedContext = CGContext(data: observedPixelsRaw, width: Int(imageSize.width), height: Int(imageSize.height),
bitsPerComponent: observedCGImage.bitsPerComponent, bytesPerRow: bytesPerRow,
space: observedColorSpace, bitmapInfo: bitmapInfo.rawValue) else {
expectedPixels.deallocate()
observedPixels.deallocate()
throw Error.unableToInitializeContext
}
expectedContext.draw(expectedCGImage, in: CGRect(origin: .zero, size: imageSize))
observedContext.draw(observedCGImage, in: CGRect(origin: .zero, size: imageSize))
let expectedBuffer = UnsafeBufferPointer(start: expectedPixels, count: numberOfPixels)
let observedBuffer = UnsafeBufferPointer(start: observedPixels, count: numberOfPixels)
var isEqual = true
if tolerance == 0 {
isEqual = expectedBuffer.elementsEqual(observedBuffer)
} else {
// Go through each pixel in turn and see if it is different
var numDiffPixels = 0
for pixel in 0 ..< numberOfPixels where expectedBuffer[pixel] != observedBuffer[pixel] {
// If this pixel is different, increment the pixel diff count and see if we have hit our limit.
numDiffPixels += 1
let percentage = 100 * Float(numDiffPixels) / Float(numberOfPixels)
if percentage > tolerance {
isEqual = false
break
}
}
}
expectedPixels.deallocate()
observedPixels.deallocate()
return isEqual
}
答案 12 :(得分：0)
我需要检测视频馈送帧中的差异并确定该差异的阈值，以便决定在我的代码中执行某些操作。您可以使用类似的像素比较来查看UIImage的pngData。
查看我的答案here
答案 13 :(得分：0)
快捷简便的解决方案
extension UIImage: Equatable {
static func ==(lhs: UIImage, rhs: UIImage) -> Bool {
return lhs.pngData() == rhs.pngData()
}
}
答案 14 :(得分：0)
Swift 5.x
您可以使用
let image: UIImage!
let anotherImage: UIImage!
image == anotherImage
答案 15 :(得分：0)
Swift5
func checkequal（img1：UIImage，imag2：UIImage）->布尔{
let data1 = img1.pngData()
let data2 = imag2.pngData()
return data1 == data2
}
答案 16 :(得分：0)
我不确定比较UIImage数据，因为它的预处理成本很高。你可以做的是子类Uimage并添加你自己的标签属性，然后在更改图像之前比较标签。分配
答案 17 :(得分：-1)
我们需要在Objective-C中使用isEqualToData方法。苹果文件指出
Two data objects are equal if they hold the same number of bytes, and if the bytes at the same position in the objects are the same.
- (BOOL)image:(UIImage *)image1 isEqualTo:(UIImage *)image2
{
NSData *data1 = UIImagePNGRepresentation(image1);
NSData *data2 = UIImagePNGRepresentation(image2);
return [data1 isEqualToData:data2];
}
答案 18 :(得分：-1)
如果您知道一个图像名称，它会对您有帮助....
CGImageRef cgImage = [imageView.image CGImage];
if (cgImage == [UIImage imageNamed:@"imagename.png"].CGImage) {
// True Statement
}
答案 19 :(得分：-2)
您还可以使用'tag'属性来识别程序后期的对象。只需设置整数值就可以了