Question

我需要加快UIImagePickerController的速度。我的应用程序将从可能的多个控制器中调用UIImagePickerController，并且在每个控制器中有两个按钮，一个用于照片库，另一个用于相机。这是我的示例应用。我尝试的一些解决方案是Apple在“并发编程指南”中推荐的。
最简单的是分配＆amp;用户按下按钮时初始化实例。这可能需要2秒才能显示相机。
解决方案尝试： - （1）我制作了一个@property（...）* imagePicker并调用了它的alloc＆amp;在viewDidAppear初始化以使其看起来很平滑，但它干扰了其他元素的加载，可能是因为它使用了相同的线程。在initWithNibName或viewDidLoad中使用时会出现更糟糕的结果。
（2）Operation queues ...不令人满意的结果。
（3）Dispatch Queues ......效果更好，但仍有明显的波动表现。
（4）performSelectorInBackground:withObject:效果不佳。除非另有建议，否则我认为我不想走向全球。我在制作UIImagePickerController的两个@properties方面没有问题。我将继续“线程编程指南”。
如果可以，请在您的解决方案中包含所有必要的内存管理实践。谢谢。

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
// (1) TRYING OPERATION QUEUES
    // (a) --- NSBlockOperation
    NSBlockOperation *NSBO_IP = [NSBlockOperation blockOperationWithBlock:^{
        NSLog(@"before");
        imagePicker = [[UIImagePickerController alloc] init];
        // 1.9, 1.6, 1.4 seconds pass between 'before' and 'after'
        // it seems this method has a dynamic technique, executes in different order every time
        NSLog(@"after");
    }];
    // (b) --- NSInvocationOperation
    NSInvocationOperation *NSIO_IP = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(loadTheImagePicker) object:nil];
    // --- Add an operation
    NSOperationQueue *queue = [[NSOperationQueue alloc] init];
    //NSLog(@"time 1");
    // (a) [queue addOperation:NSBO_IP];
    // (b) [queue addOperation:NSIO_IP];
    //NSLog(@"time 2");
// (2)TRYING DISPATCH QUEUES
    // (a) --- GCD call  (do I need to release 'myQueue' at some point since this is C-level call?)
/*
    NSLog(@"time 1");
    dispatch_queue_t myQueue = dispatch_queue_create("My Queue", NULL);
    dispatch_async(myQueue, ^{
        imagePicker = [[UIImagePickerController alloc] init];
        // 1.2, 1.2, 1.2, 1.4 seconds significant increase over Operation Queues
        // a solid constant executing technique, executes very consistently
    });
    NSLog(@"time 2");
*/
// (3)TRYING performSelectorInBackground:withObject  (not recommended?)
    NSLog(@"time 1");
    [self performSelectorInBackground:@selector(loadTheImagePicker) withObject:nil];
    // 1.3, 1.7, 1.3 seconds pass between 'before' and 'after'
    NSLog(@"time 2");
// RESULTS REFLECTED IN LINE BELOW !
    [self changeText:self];  // text does not change on time when trying to alloc & init an ImagePickerController
}
    - (void)loadTheImagePicker
    {
    NSLog(@"before");
    imagePicker = [[UIImagePickerController alloc] init];
    // --- NSInvocationOperation used
    // 1.6, 1.2, 1.4 seconds pass between 'before' and 'after'
    // this method has a more constant executing technique, as far as order of executions
    // --- NSInvocationOperation used
    NSLog(@"after");
}

Answer 1

from @Murat's answer in a comment:

I found the solution. This question has already been answered. It seems when connected to Xcode debugger the [UIImagePickerController alloc] init] takes much longer to execute than when running the App without Xcode.

My solution is still to keep @property and do the alloc & init in the viewDidLoad method.

The other solution is here: UIViewController - mysteriously slow to load

moved this to an answer as I almost missed it as a comment.

加载UIImagePickerController更快？

1 个答案: