比较图像

isEqual:方法是确定两个图像是否包含相同图像数据的唯一可靠方法。你创建的图像对象可能彼此不同，即使使用相同的缓存图像数据初始化它们也是如此。确定其相等性的唯一方法是使用 isEqual:方法，该方法比较实际图像数据。清单 1 说明了比较图像的正确和错误方法。

来源： Apple 文档

迅速

// Load the same image twice.
let image1 = UIImage(named: "MyImage")
let image2 = UIImage(named: "MyImage")

// The image objects may be different, but the contents are still equal
if let image1 = image1, image1.isEqual(image2) {
    // Correct. This technique compares the image data correctly.
}

if image1 == image2 {
    // Incorrect! Direct object comparisons may not work.
}

Objective-C

// Load the same image twice.
UIImage* image1 = [UIImage imageNamed:@"MyImage"];
UIImage* image2 = [UIImage imageNamed:@"MyImage"];
 
// The image objects may be different, but the contents are still equal
if ([image1 isEqual:image2]) {
   // Correct. This technique compares the image data correctly.
}
 
if (image1 == image2) {
   // Incorrect! Direct object comparisons may not work.
}