可能是什麼建立在這個錯誤的原因 - 「爲i386" 硬件架構未定義的符號

這是我第一次與位置服務工作，我打這個連接錯誤：可能是什麼建立在這個錯誤的原因 - 「爲i386" 硬件架構未定義的符號

Undefined symbols for architecture i386: "_OBJC_CLASS_$_CLLocationManager"

我已經加入#import <CoreLocation/CoreLocation.h>，並添加以下行的viewDidLoad

CLLocationManager *manager = [[CLLocationManager alloc] init]; 
manager.delegate = self; 
[manager startUpdatingLocation]; 
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES; 

if (![CLLocationManager locationServicesEnabled]){ 
    UIAlertView *servicesDisabledAlert = [[UIAlertView alloc] initWithTitle:@"Location Services Disabled" message:@"You currently have all location services for this device disabled. If you proceed, you will be asked to confirm whether location services should be reenabled." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil]; 
    [servicesDisabledAlert show]; 
    [servicesDisabledAlert release]; 
} 
[manager release];

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