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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114
｜
第
3
章
3.14
当用户进入或离开某个位置时获得通知
问题
当用户进入或退出一个特定区域时如何获得通知？
解决方案
我们的程序能够做到在不运行的时候也能接收到通知。这需要以下几个步骤：
1.
在项目导航窗口中，选中顶部的项目文件，打开项目设置窗口（在
Xcode
窗口
的左边，如图
3-3
所示）。
图
3
-
3
：位于项目导航窗口顶部的项目文件
2.
从
Target
列表中选择项目的
target
。
3.
点击
Capabilities
标签。
4.
找到“
Background Modes
”。
5.
勾选“
Location updates
”选项，如图
3-4
所示。
输入
｜
115
图
3
-
4
：选择背景模式的 “Location updates”
另外，我们还需要在项目的
Info.plist
文件中增加一个
NSLocationAlwaysUsageDesc
ription
条目
,
并在条目的值中填写程序使用用户位置信息的用途。
编辑
ViewController.swift
的代码如下：
import UIKit
import CoreLocation
class ViewController: UIViewController, CLLocationManagerDelegate {
var locationManager ...
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