关于UIImagePickerController读取照片时的卡顿和照片压缩

UIImagePickerController

-(void)imagePickerController:(UIImagePickerController*)picker didFinishPickingMediaWithInfo:(NSDictionary *)info

{

   //关闭相册界面   //这个位置解决使用图片时的内存徒增的现象

    [pickerdismissViewControllerAnimated:YEScompletion:nil];

   NSString*type = [infoobjectForKey:UIImagePickerControllerMediaType];

   //当选择的类型是图片

    if ([type isEqualToString:@"public.image"])

    {

       //先把图片转成NSData

       UIImage* image = [infoobjectForKey:@"UIImagePickerControllerOriginalImage"];

        //图片比例压缩的一套方法

       CGSizesize = [LW_ImageCompressionget_ImageCompressionProportion:image];

        image = [imageimageByScalingAndCroppingForSize:size];

        NSData *data = UIImagePNGRepresentation(image);

        if (data == nil)

        {

            data = UIImageJPEGRepresentation(image, 0.25);

        }

       //图片保存的路径

       //这里将图片放在沙盒的documents文件夹中

       NSString* DocumentsPath = [NSHomeDirectory()stringByAppendingPathComponent:@"Documents"];

        //文件管理器

        NSFileManager *fileManager = [NSFileManager defaultManager];

       //把刚刚图片转换的data对象拷贝至沙盒中 并保存为image.png

        [fileManagercreateDirectoryAtPath:DocumentsPathwithIntermediateDirectories:YESattributes:nilerror:nil];

        [fileManagercreateFileAtPath:[DocumentsPathstringByAppendingString:@"/image.png"]contents:dataattributes:nil];

        //GET THE IMAGE

    }

}

+(CGSize)get_ImageCompressionProportion:(UIImage *)image

{

    CGSize size = image.size;

    CGFloat HBL = ScreenHeight / size.height;

    CGFloat WBL = ScreenWidth / size.width;

    if (size.width <= ScreenWidth && size.height <= ScreenHeight) {

        return size;

    }

    else if (size.width > ScreenWidth && size.height <= ScreenHeight) {

        size.width = ScreenWidth;

        size.height = size.height * WBL;

        NSString * str = [NSString stringWithFormat:@"%.0f",size.height];

        size.height = [str floatValue];

    }

    else if (size.height > ScreenHeight && size.width <= ScreenWidth) {

        size.height = ScreenHeight;

        size.width = size.width * HBL;

        NSString * str = [NSString stringWithFormat:@"%.0f",size.width];

        size.width = [str floatValue];

    }

    else if (size.height > ScreenHeight && size.width > ScreenWidth) {

        if (HBL < WBL) {

            size.height = ScreenHeight;

            size.width = size.width * HBL;

            NSString * str = [NSString stringWithFormat:@"%.0f",size.width];

            size.width = [str floatValue];

        }

        else

        {

            size.width = ScreenWidth;

            size.height = size.height * WBL;

            NSString * str = [NSString stringWithFormat:@"%.0f",size.height];

            size.height = [str floatValue];

        }

    }

    return size;

}