ios - UIGraphicsBeginImageContextWithOptions 不捕获阴影/渐变

Question

问题

我正在使用 UIGraphicsBeginImageContextWithOptions 将屏幕截图保存到 UIImage 中。虽然这有效，但生成的 UIImage 缺少任何阴影和渐变。

如何让它同时对图层内容进行截图？

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显示问题的测试代码

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#import "ViewController.h"
#import <QuartzCore/QuartzCore.h>

@implementation ViewController

- (void)viewDidLoad {
    //super
    [super viewDidLoad];

    //background
    self.view.backgroundColor = [UIColor whiteColor];

    //container
    UIView *container = [[UIView alloc] initWithFrame:CGRectMake(10, 10, 300, 200)];
    container.backgroundColor = [UIColor blackColor];
    [self.view addSubview:container];

    //circle
    UIView *circle = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 10, 10)];
    circle.backgroundColor = [UIColor whiteColor];
    circle.layer.cornerRadius = 5;
    circle.layer.shadowColor = [UIColor redColor].CGColor;
    circle.layer.shadowOffset = CGSizeZero;
    circle.layer.shadowOpacity = 1;
    circle.layer.shadowRadius = 10;
    circle.layer.shadowPath = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(-10, -10, 30, 30)].CGPath;
    [container addSubview:circle];

    //screenshot
    UIGraphicsBeginImageContextWithOptions(container.bounds.size, container.opaque, 0.0);
    [container.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    //image view
    UIImageView *iv = [[UIImageView alloc] initWithFrame:CGRectMake(10, 568-200-20-10, 300, 200)];
    iv.image = screenshot;
    [self.view addSubview:iv];
}

@end

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显示问题的模拟器屏幕截图

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顶部区域是原始 View 。底部区域是带有屏幕截图的 UIImageView。

Answer 1

在这一行中，

UIGraphicsBeginImageContextWithOptions(container.bounds.size, container.opaque, 0.0);

put NO instead of container.opaque

使用这个方法，

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

    if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)]) {
        UIGraphicsBeginImageContextWithOptions(view.bounds.size, NO, 0.0);
    } else {
        UIGraphicsBeginImageContext(view.bounds.size);
    }

    [view.layer renderInContext:UIGraphicsGetCurrentContext()];

    UIImage * img = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return img;
}