UIImage + ImageEffects无法在设备上工作

Question

我有一个模态视图，我想要显示计算结果。为了让所有的iOS7看起来，我想要一个带有模糊背景的弹出视图的有色背景。

我设法使用苹果公司的“UIImage + ImageEffects.h/m”文件工作。

这是模态视图的viewDidLoad中：

- (void)viewDidLoad { 

    [super viewDidLoad]; 

    /* How it works 

    self.image is a screenshot of the VC presenting the modal view 

    1- we set the background as the screenshot of the previous viewControler 
    2- we hide the popup view 
    3- we set the background of the popup as a blured snapshot of its container view (self.view) 
    4- we unhide the popup view and set its radius 
    5- we create a tinted version of the background image (what we got from the previous view controller 
    6- we set the background of self.view to the tinted version 


    */ 

    // *** 1 *** 

    self.view.backgroundColor=[UIColor colorWithPatternImage:self.image]; 


    // *** 2 *** 

    self.containerView.hidden=YES; 


    // *** 3 *** 

    UIImage *pepe=[self bluredImageFromView:self.containerView withBackground:self.view withBackgroundTintColor:[UIColor colorWithWhite:1 alpha:0.75]]; 
    self.containerView.backgroundColor=[UIColor colorWithPatternImage:pepe]; 

    // *** 4 *** 

    self.containerView.hidden=NO; 
    self.containerView.layer.cornerRadius=4.5f; 

    // *** 5 *** 

    UIImage *tintedBackground =[self.image applyBlurWithRadius:0 
                 tintColor:[UIColor colorWithRed:0.85 green:0.85 blue:0.85 alpha:0.35] 
              saturationDeltaFactor:1.8 
                 maskImage:nil]; 
    // *** 6 *** 

    self.view.backgroundColor=[UIColor colorWithPatternImage:tintedBackground]; 


} 

它工作得很好的模拟器但是当我试图onmy iPhone（4S），提出了模态视图的时候，我有一个黑色的屏幕。没有错误，没有抱怨从控制台，没有任何。

有什么想法？

编辑

我添加代码：

if (!self.image) NSLog (@"self.image is empty"); 

在viewDidLoad中

之初

看来，在模拟器上self.image不为零，而在设备上它是。我尝试从父VC上的prepareForSegue实例化self.image，但不起作用。

Answer 1

我不知道你的bluredImageFromView工作，但也有安全性（沙盒）仿真和实际iOS设备（特别是resizableSnapshotViewFromRect:和drawViewHierarchyInRect:）之间的差异这或许可以解释为什么它的工作原理（但是不能够）
看看这个thread在raywenderlich.com有人从Apple Developer技术支持得到的建议。这个示例代码显然来自Apple。

- (IBAction)doBlurAndCrop:(id)sender { 

UIImage *snapshotImage; 

    /* draw the image of all the views below our view */ 
UIGraphicsBeginImageContextWithOptions(self.sourceImageView.bounds.size, NO, 0); 
BOOL successfulDrawHierarchy = [self.sourceImageView drawViewHierarchyInRect:self.sourceImageView.bounds afterScreenUpdates:YES]; 
if (successfulDrawHierarchy) { 
    snapshotImage = UIGraphicsGetImageFromCurrentImageContext(); 
} else { 
    NSLog(@"drawViewHierarchyInRect:afterScreenUpdates: failed - there's nothing to draw..."); 
} 
UIGraphicsEndImageContext(); 

if (successfulDrawHierarchy) { 

     /* calculate the coordinates of the rectangle we're interested in within the returned image */ 
    CGRect cropRect = CGRectOffset(self.targetImageView.frame, - self.sourceImageView.frame.origin.x, - self.sourceImageView.frame.origin.y); 

     /* draw the cropped section with a clipping region */ 
    UIGraphicsBeginImageContextWithOptions(cropRect.size, YES, 0); 
    CGContextRef context = UIGraphicsGetCurrentContext(); 
    CGContextClipToRect(context, CGRectMake(0, 0, cropRect.size.width, cropRect.size.height)); 
    CGRect targetRectangeForCrop = CGRectMake(-cropRect.origin.x, -cropRect.origin.y, snapshotImage.size.width, snapshotImage.size.height); 
    [snapshotImage drawInRect:targetRectangeForCrop]; 
    UIImage *croppedSnapshotImage = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 

     /* apply a special effect to the resulting image and copy it into place on screen */ 
    UIColor *tintColor = [UIColor colorWithWhite:1.0 alpha:0.3]; 
    self.targetImageView.image = [croppedSnapshotImage applyBlurWithRadius:5 tintColor:tintColor saturationDeltaFactor:1.8 maskImage:nil]; 
} 
}