iOS获取指定位置图像

//指定视图截图

-(UIImage *)screenShotView:(UIView *)view{

    UIImage *imageRet = [[UIImage alloc]init];

    UIGraphicsBeginImageContextWithOptions(view.frame.size, false, 0.0);

    [view.layer renderInContext:UIGraphicsGetCurrentContext()];

    imageRet = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    

    return imageRet;

}

//获得某个范围内的屏幕图像

- (UIImage *)imageFromView: (UIView *) theView   atFrame:(CGRect)rect

{

    UIGraphicsBeginImageContext(theView.frame.size);

    //用这个不会失真

//    UIGraphicsBeginImageContextWithOptions(theView.frame.size, false, 0.0);

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSaveGState(context);

    //这里其实就是裁剪

    UIRectClip(rect);

    [theView.layer renderInContext:context];

    //设定颜色：透明

    [[UIColor clearColor] setFill];

    

    UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();

    

    //获取 某图片 指定范围(rect)内的cgImage

    CGImageRef cgImage = CGImageCreateWithImageInRect(theImage.CGImage, rect);

    UIImage * returnImage = [UIImage imageWithCGImage:cgImage];

    CGImageRelease(cgImage);

    UIGraphicsEndImageContext();

    

    return  returnImage;

}

本文地址：https://blog.csdn.net/ios_xumin/article/details/108174043