January 2020
Intermediate to advanced
356 pages
6h 4m
Chinese
Content preview from Swift游戏开发经典实例
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162
｜
第
5
章
接下来是调用的代码：
//
从资源包中读取所有
.png
文件的列表
let urls = Bundle.main
.urls(forResourcesWithExtension: "png",
subdirectory: nil) ?? []
//
装载整个文件列表
AssetLoader.loadAssets(at: urls) {
(url, data, error) -> Void in
//
遍历每个
URL
并依次执行这个块
if let data = data {
print("Loaded resource \(url.lastPathComponent) (\(data.count) bytes)")
} else if let error = error {
print("Failed to load resource \(url.lastPathComponent): \(error)")
} else {
fatalError("Didn't get data or an error; this should not happen!")
}
}
讨论
大文件的加载会耗用较长时间，我们当然不希望因为加载磁盘文件而让用户觉得屏
幕似乎被“冻住”了。为了解决这个问题，我们用一个专门的类在后台中处理资源
的加载。
AssetLoader
类创建了一个执行队列并用这个队列来进行资源的加载。当
资源装载结束，指定的块会在每一
URL
上执行（在主线程中）。 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.