iphone MPMoviePlayerViewController CGContext错误 [英] iphone MPMoviePlayerViewController CGContext Errors

问题描述

我正在为iPhone编写一个应用程序，它将使用 MPMoviePlayerViewController 播放一些电影。到目前为止，我已经得到它来播放电影，但它在调试器中抛出一些错误，所有错误都以 CGContext 开头。我试图解决它已经破坏了我的大脑。以下是我的代码的详细信息：

I am writing an app for the iPhone that will play some movies utilizing MPMoviePlayerViewController. So far I have gotten it to play movies, however it is throwing some errors in the debugger that all start with CGContext. I have wracked my brain in trying to fix it. Here are the details of my code:

.h文件：

#import <UIKit/UIKit.h>
#import <MediaPlayer/MediaPlayer.h>
@interface MovieViewController : UIViewController {
    MPMoviePlayerViewController *playerController;
}

-(IBAction) playMovie:(id)sender;

.m文件：

@interface MovieViewController ()
@end
@implementation

-(IBAction)playMovie:(id)sender {
NSURL *url = [NSURL fileURLWithPath:[[NSBundle mainBundle]
                                     pathForResource:@"moviename" ofType:@"mp4"]];
playerController =  [[MPMoviePlayerViewController alloc]
                     initWithContentURL:url];
[self presentMoviePlayerViewControllerAnimated:playerController];
playerController.moviePlayer.movieSourceType = MPMovieSourceTypeFile;
[playerController.moviePlayer play];
playerController = nil; 
}

当我运行程序时，电影将播放，但是当代码执行时line： playerController = [[MPMoviePlayerViewController alloc] initWithContentURL：url]; 发生以下错误：

When I run the program the movie will play, however when the code executes the line: playerController = [[MPMoviePlayerViewController alloc] initWithContentURL:url]; the following errors occur:

<Error>: CGContextSaveGState: invalid context 0x0
<Error>: CGContextClipToRect: invalid context 0x0
<Error>: CGContextTranslateCTM: invalid context 0x0
<Error>: CGContextDrawShading: invalid context 0x0
<Error>: CGContextRestoreGState: invalid context 0x0

我知道无效的上下文0x0 意味着这些特定变量没有值，但我不知道如何解决这个问题。任何帮助将不胜感激。

I do know that invalid context 0x0 means that those specific variables do not have a value, but I have no idea how to remedy this. Any help would be greatly appreciated.

推荐答案

我遇到了同样的问题。仅仅这样说：

I was having the same issue. Merely saying this:

MPMoviePlayerViewController* mpvc = 
    [[MPMoviePlayerViewController alloc] initWithContentURL: m];

导致这些无效上下文错误消息。视图控制器的视图（全屏播放器）确实出现了，播放电影没问题;唯一的问题是这些错误消息，我不想在控制台中显示。

was causing these invalid context error messages. The view controller's view (the fullscreen player) did appear when presented, and played the movie no problem; the only issue was these error messages, which I didn't want showing up in the console.

从Norman的解决方案中得到一个提示，我只是简单地将调用包裹起来绘制上下文，如下所示：

Taking a hint from Norman's solution, I simply wrapped the call in an artificial drawing context, like this:

UIGraphicsBeginImageContext(CGSizeMake(1,1));
MPMoviePlayerViewController* mpvc = 
    [[MPMoviePlayerViewController alloc] initWithContentURL: m];
UIGraphicsEndImageContext();

这很愚蠢，但确实有效。

It's silly, but it works.

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