Core Location在iOS 8中的变化---Swift

一直以来,定位的实现都非常的简单和一致:

Objective-C的实现:

#import "ViewController.h"
@import CoreLocation; //引入库文件

@interface ViewController () <CLLocationManagerDelegate> //遵守协议
@property (strong, nonatomic) CLLocationManager *locationManager; //定义Location Manager
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    //初始化Manager并开始定位
    self.locationManager = [[CLLocationManager alloc] init];
    self.locationManager.delegate = self;
    [self.locationManager startUpdatingLocation];
}

//Delegate的协议方法
- (void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations
{
    NSLog(@"%@", [locations lastObject]);
}

- (void)locationManager:(CLLocationManager *)manager didFailWithError:(NSError *)error
{
    NSLog(@"error = %@",[error description]);
}

@end

Swift的实现:

import UIKit
import CoreLocation

class ViewController: UIViewController, CLLocationManagerDelegate {
    
    let locationManager:CLLocationManager = CLLocationManager()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        locationManager.delegate = self
        locationManager.startUpdatingLocation();
    }
    
    func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {
        println("new Location = \(locations.last)")
    }
    
    func locationManager(manager: CLLocationManager!, didFailWithError error: NSError!) {
        println("error = \(error.description)")
    }
}

但是在iOS8的情况下,任何代理方法都是沉默的---既不能得到失败的原因或者警告,也不能得到位置信息.App也不会有请求允许使用位置信息的许可.非常的和谐.
在iOS8的系统中需要做两件事情才能让定位能够生效:

1. 在Info.plist添加一对关键字来许可位置服务.NSLocationAlwaysUsageDescription和NSLocationWhenInUseUsageDescription,两个关键字对应的字符串可以是随意的,一般只要添加一个关键字即可,因为有AlwaysUsage那么WhenInUse情况下也能定位,反之则不能适用.

2. 在代码中请求许可.

Objective-C的实现:

    if ([self.locationManager respondsToSelector:@selector(requestWhenInUseAuthorization)]) {
        [self.locationManager requestWhenInUseAuthorization];
    }
    //或者
    if ([self.locationManager respondsToSelector:@selector(requestAlwaysAuthorization)]) {
        [self.locationManager requestAlwaysAuthorization];
    }

Swift的实现:

        //iOS8中的方法,不然是无法定位的
        if locationManager.respondsToSelector(Selector("requestWhenInUseAuthorization")) {
            locationManager.requestWhenInUseAuthorization()
        }
        //或者
        if locationManager.respondsToSelector(Selector("requestAlwaysAuthorization")) {
            locationManager.requestAlwaysAuthorization()
        }

更改地理位置的认证状态

如果最开始的时候设置的是WhenInUse, 而后需要使用Always,那么就需要在Plist和代码中更改状态

Objective-C的实现:

if ([self.locationManager respondsToSelector:@selector(requestAlwaysAuthorization)]) {
        [self requestAlwaysAuthorization];
    }

- (void)requestAlwaysAuthorization
{
    CLAuthorizationStatus status = [CLLocationManager authorizationStatus];
    //如果状态是没有获准就弹出一个Alert
    if (status == kCLAuthorizationStatusAuthorizedWhenInUse || status == kCLAuthorizationStatusDenied) {
        NSString *title;
        title = (status == kCLAuthorizationStatusDenied) ? @"定位是关闭状态" : @"后台定位没有开启";
        NSString *message = @"需要开启Alway的定位服务";
        UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:title
                                                            message:message
                                                           delegate:self
                                                  cancelButtonTitle:@"取消"
                                                  otherButtonTitles:@"设置", nil];
        [alertView show];
    }
    else if (status == kCLAuthorizationStatusNotDetermined) {
        [self.locationManager requestAlwaysAuthorization];
    }
}
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if (buttonIndex == 1) {
        // 跳到设置界面
        NSURL *settingsURL = [NSURL URLWithString:UIApplicationOpenSettingsURLString];
        [[UIApplication sharedApplication] openURL:settingsURL];
    }
}

Swift的实现:

        if locationManager.respondsToSelector(Selector("requestAlwaysAuthorization")) {
            requestAlwaysAuthorization()
        }

    func requestAlwaysAuthorization() {
        let status = CLLocationManager.authorizationStatus()
        if status == .Denied || status == .AuthorizedWhenInUse {
            let title = (status == .Denied) ? "定位是关闭状态" : "后台定位没有开启"
            let message = "需要开启Alway的定位服务"
            UIAlertView(title: title, message: message, delegate:self, cancelButtonTitle: "取消", otherButtonTitles: "设置")
        } else {
            locationManager.requestAlwaysAuthorization()
        }
    }
    
    func alertView(alertView: UIAlertView, clickedButtonAtIndex buttonIndex: Int) {
        if buttonIndex == 1 {
            UIApplication.sharedApplication().openURL(NSURL(string: UIApplicationOpenSettingsURLString)!)
        }
    }