比较两个UIImage是否相等

转成NSData

- (BOOL)image:(UIImage *)image1 isEqualTo:(UIImage *)image2 {
    NSData *data1 = UIImagePNGRepresentation(image1);
    NSData *data2 = UIImagePNGRepresentation(image2);
    
    return [data1 isEqual:data2];
}