Question

我有一个模态视图，我想在其中显示计算结果。为了使所有iOS7看起来，我想要一个带有背景的弹出视图的有色背景。

我设法使用文件＆＃34; UIImage + ImageEffects .h / m＆＃34;来自苹果。

这是模态视图的viewDidLoad：

- (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];


}

它在模拟器上工作得非常好但是当我尝试使用我的iPhone（4S）时，当呈现模态视图时，我有一个黑屏。没有错误，没有从控制台抱怨，没有任何东西。

有什么想法吗？

修改

我添加了代码：

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

在viewDidLoad的最开头

似乎在模拟器上，self.image不是零，而在设备上它是。我试图在父VC上从 prepareForSegue 实例化self.image但是没有用。

Answer 1

我不知道您的bluredImageFromView是如何工作的，但模拟器与实际的iOS设备（尤其是resizableSnapshotViewFromRect:和drawViewHierarchyInRect:）之间存在安全性（沙盒）差异可以解释为什么它有效（但不是在设备上。）
在raywenderlich.com查看此thread，其中有人从Apple Developer技术支持获得建议。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];
}
}

UIImage + ImageEffects不能在设备上运行

1 个答案: