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不导入框架为什么有时崩溃有时不崩溃

  情况一:地理编码

    storyboard:

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  代码如下(项目并未导入MapKit框架,但运行程序并不崩溃):

      

 1 #import "ViewController.h"
 2 #import <CoreLocation/CoreLocation.h>
 3 
 4 @interface ViewController ()
 5 @property (weak, nonatomic) IBOutlet UITextField *addressTF;
 6 @property (weak, nonatomic) IBOutlet UILabel *longitudeLabel;
 7 @property (weak, nonatomic) IBOutlet UILabel *latitudeLabel;
 8 @property (weak, nonatomic) IBOutlet UILabel *detailLabel;
 9 
10 @end
11 
12 @implementation ViewController
13 
14 - (void)viewDidLoad {
15     [super viewDidLoad];
16     // Do any additional setup after loading the view, typically from a nib.
17 }
18 
19 //地理编码
20 - (IBAction)geocode {
21     //创建地理编码对象
22     CLGeocoder * geocoder = [[CLGeocoder alloc]init];
23     
24     if (self.addressTF.text == nil) {
25         return ;
26     }
27     
28     [geocoder geocodeAddressString:self.addressTF.text completionHandler:^(NSArray<CLPlacemark *> * _Nullable placemarks, NSError * _Nullable error) {
29         if (error) {
30             NSLog(@"%@",error);
31             return ;
32         }
33         //获取地标 CLPlacemark
34         for (CLPlacemark * placemark in placemarks) {
35             self.longitudeLabel.text = [NSString stringWithFormat:@"%f",placemark.location.coordinate.longitude];
36             self.latitudeLabel.text = [NSString stringWithFormat:@"%f",placemark.location.coordinate.latitude];
37             self.detailLabel.text = placemark.name;//具体地名
38             NSLog(@"%@",placemark.locality);//城市名
39         }
40         
41     }];
42     
43     
44 }
45 
46 @end

  情况二:添加地图View

    storyboard:

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  代码(项目没有导入框架,但程序崩溃):

 1 #import "ViewController.h"
 2 #import <MapKit/MapKit.h>
 3 
 4 @interface ViewController ()
 5 
 6 @end
 7 
 8 @implementation ViewController
 9 
10 - (void)viewDidLoad {
11     [super viewDidLoad];
12     // Do any additional setup after loading the view, typically from a nib.
13 }
14 
15 
16 - (void)didReceiveMemoryWarning {
17     [super didReceiveMemoryWarning];
18     // Dispose of any resources that can be recreated.
19 }
20 
21 
22 @end

  程序崩溃报错:

  *** Terminating app due to uncaught exception ‘NSInvalidUnarchiveOperationException‘, reason: ‘Could not instantiate class named MKMapView‘

  导入MapKit框架后,则能成功运行.

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  为什么有的时候崩溃而有的时候不会?

  因为在XCode5之后,在你#import <MapKit/MapKit.h>之后,程序默认帮助程序员导入框架.但由于情景二中程序运行后,先走的是storyboard中箭头指向的控制器,发现有MKMapView控件,而程序那时候还没有自动导入框架,所以崩溃. 而情景一中,storyboard中的控件并没有涉及到任何相关的控件,而是在代码中导入了头文件之后才使用了CoreLocation相关的方法,那个时候程序已经自动帮我们导入了框架,所以不会崩溃.

  所以,只要在storyboard的中使用了UIKit之外的框架,必须手动在项目中导入.

 

不导入框架为什么有时崩溃有时不崩溃