英文:
Objective-C equivalent of simple Swift video player does not show video
问题
我正在创建一个简单的故事板，用于播放一个mp4视频。在Swift中，这个代码工作得很正常，但当我尝试在Objective-C中做完全相同的事情时，什么都不会发生。有人能看看我从Swift转换成Objective-C的代码中是否有什么问题吗？
注：
- 两个项目都只有视图控制器的实现
- 视频文件anim2.mp4确实包含在两个项目中
- 出于技术原因，视频播放器必须使用Objective-C
以下是代码的翻译部分：
// Swift implementation
#import <UIKit/UIKit.h>
#import <AVKit/AVKit.h>
#import <AVFoundation/AVFoundation.h>
@interface ViewController : UIViewController
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
NSString* path = [[NSBundle mainBundle] pathForResource:@"anim2" ofType:@"mp4"];
NSURL* url = [NSURL fileURLWithPath:path isDirectory:NO];
AVPlayer* player = [[AVPlayer alloc] initWithURL:url];
AVPlayerLayer* playerLayer = [AVPlayerLayer playerLayerWithPlayer:player];
playerLayer.frame = self.view.bounds;
[self.view.layer addSublayer:playerLayer];
[player play];
}
@end
请注意，代码的翻译部分已经从Swift转换为Objective-C，并修复了一些可能引起问题的语法。如果仍然有问题，请检查您的项目设置和文件路径等方面，确保视频文件正确包含在Objective-C项目中。
英文:
I'm creating a simple storyboard that plays an mp4 video. This works as expected in Swift, but when I try to do the exact same thing in Objective-C nothing happens.
Can anyone see if I'm doing anything wrong in the Objective-C code converted from Swift?
Notes:
- Both projects are empty except for the view controller implementation
- The video file anim2.mp4 is indeed included in both projects
- For technical reasons, the video player must utilize Objective-C
Code:
// Swift implementation
import UIKit
import AVKit
import AVFoundation
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let path = Bundle.main.path(forResource: "anim2", ofType:"mp4");
let url = NSURL(fileURLWithPath: path!) as URL;
let player = AVPlayer(url: url);
let playerLayer = AVPlayerLayer(player: player);
playerLayer.frame = self.view.bounds;
self.view.layer.addSublayer(playerLayer);
player.play();
}
}
// Objective-C implementation
#import "ViewController.h"
#import <AVKit/AVKit.h>
#import <AVFoundation/AVFoundation.h>
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
NSString* path = [[NSBundle mainBundle] pathForResource:@"anim2" ofType:@"mp4"];
NSURL* url = [NSURL fileURLWithPath:path isDirectory:false];
AVPlayer* player = [[AVPlayer alloc] initWithURL:url];
AVPlayerLayer* playerLayer = [[AVPlayerLayer alloc] initWithLayer:player];
playerLayer.frame = self.view.bounds;
[self.view.layer addSublayer:playerLayer];
[player play];
}
@end
答案1
得分: 1
这行代码不同：
AVPlayerLayer* playerLayer = [[AVPlayerLayer alloc] initWithLayer:player];
这试图将AVPlayer视为CALayer，这将悄悄失败。您在这里没有警告，因为initWithLayer:将id作为其类型。
您的意思是：
AVPlayerLayer* playerLayer = [AVPlayerLayer playerLayerWithPlayer: player];
英文:
This line is not the same:
AVPlayerLayer* playerLayer = [[AVPlayerLayer alloc] initWithLayer:player];
That tries to treat an AVPlayer as a CALayer, which is going to quietly fail. You don't get a warning here because initWithLayer: takes id as its type.
What you meant was:
AVPlayerLayer* playerLayer = [AVPlayerLayer playerLayerWithPlayer: player];
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