視圖快照不渲染

Question

我試圖獲取另一個控制器視圖的快照以在動畫中使用。我使用下面的代碼，但我什麼也看不見，但這種觀點的背景顏色，並沒有其子視圖（兩個按鈕，一個文本視圖和標籤）：

- (void)viewDidAppear:(BOOL)animated { 
    [super viewDidAppear:animated]; 
    FirstPageController *fpController = [self.storyboard instantiateViewControllerWithIdentifier:@"FirstPage"]; 
    UIGraphicsBeginImageContext(fpController.view.bounds.size); 
    NSLog(@"%@",fpController.view.subviews); 
    [fpController.view.layer renderInContext:UIGraphicsGetCurrentContext()]; 
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 

    CGSize destinationSize = CGSizeMake(90, 122); 

    UIGraphicsBeginImageContext(destinationSize); 
    [viewImage drawInRect:CGRectMake(0,0,destinationSize.width,destinationSize.height)]; 
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 
    self.imageView2 = [[UIImageView alloc] initWithImage:newImage]; 
    self.imageView2.center = self.view.center; 
    [self.view addSubview:self.imageView2]; 
    NSLog(@"%@",NSStringFromCGSize(self.imageView2.image.size)); 
} 

我記錄的所有相關的東西，fpController，imageView，圖像和所有正確記錄。

編輯完成後：如果我切換到當前控制器的視圖，它工作正常，所以我認爲這與獲取不在屏幕上的視圖的快照有關。可以這樣做嗎？

Answer 1

UIGraphicsBeginImageContextWithOptions(fpController.view.bounds.size, NO, 0.0); 


UIGraphicsBeginImageContextWithOptions(destinationSize, NO, 0.0); 

使用此兩行而不是UIGraphicsBeginImageContext(fpController.view.bounds.size);

UIGraphicsBeginImageContext(destinationSize); respectively 

希望它能幫助是你

Answer 2

希望這將幫助你：

CGSize textcontent =CGSizeMake(width, height); 
UIGraphicsBeginImageContext(textcontent); 
if ([UIScreen instancesRespondToSelector:@selector(scale)] && [[UIScreen mainScreen] scale] == 2.0f) 
{ 
    UIGraphicsBeginImageContextWithOptions(textcontent, YES, 1.0f); 
} 
else 
{ 
    UIGraphicsBeginImageContext(textcontent); 
} 
    [image.layer renderInContext:UIGraphicsGetCurrentContext()]; 
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 
    return viewImage; 

Answer 3

我找到了一個方法，使這項工作，儘管它看起來像一個黑客。我將我想要渲染的視圖添加爲視圖的子視圖，進行渲染，然後刪除視圖。它從來沒有在屏幕上看到，所以視覺上，它很好。我只是想知道是否有更好的方法。

- (void)viewDidAppear:(BOOL)animated { 
    [super viewDidAppear:animated]; 
    self.fpController = [self.storyboard instantiateViewControllerWithIdentifier:@"FirstPage"]; 

    [self.view insertSubview:self.fpController.view belowSubview:self.view]; 

    UIGraphicsBeginImageContext(self.fpController.view.bounds.size); 
    [self.fpController.view.layer renderInContext:UIGraphicsGetCurrentContext()]; 
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 

    [self.fpController.view removeFromSuperview]; 

    self.imageView2 = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 90, 122)]; 
    self.imageView2.image = viewImage; 
    [self.pageView insertSubview:self.imageView2 belowSubview:self.imageView]; 
}