停止活动指示器 当 uitextview 使用谷歌 API 加载当前位置时

Question

当uitextview使用Google API加载当前位置时，如何停止UIActivityIndicatorView。

这是我的代码：

@implementation ViewController
@synthesize loctxt;
 - (void)viewDidLoad {
        loctxt=[[UITextView alloc]initWithFrame:CGRectMake(10, 50, 220, 30)];
        loctxt.backgroundColor=[UIColor whiteColor];
        loctxt.delegate=self;
        [self.view addSubview:loctxt];
        locbtn=[[UIButton alloc]initWithFrame:CGRectMake(240, 50, 40, 30)];
        [locbtn addTarget:self action:@selector(clickToGetLocation)forControlEvents:UIControlEventTouchUpInside];
        locbtn.backgroundColor=[UIColor grayColor];
        [locbtn setImage:[UIImage imageNamed:@"sst14.gif"] forState:UIControlStateNormal];
        [self.view addSubview:locbtn];
        [super viewDidLoad];
        // Do any additional setup after loading the view, typically from a nib.
    }
    - (void)clickToGetLocation {
        spinner = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(0,100, 20, 20)];
        [spinner setActivityIndicatorViewStyle:UIActivityIndicatorViewStyleGray];
        [self.view addSubview:spinner]; 
         **[spinner startAnimating];**

        AppDelegate *delegate=(AppDelegate *)[[UIApplication sharedApplication]delegate];
        NSString *urlString = [NSString stringWithFormat:@"http://maps.google.com/maps/geo?q=%f,%f&output=csv",delegate.latitude, delegate.longitude];
        NSError* error;
        NSString *locationString = [NSString stringWithContentsOfURL:[NSURL URLWithString:urlString] encoding:NSASCIIStringEncoding error:&error];
        NSLog(@"%@",locationString);
        locationString = [locationString stringByReplacingOccurrencesOfString:@""" withString:@""];
        **self.loctxt.text=[locationString substringFromIndex:6];**
    //if i use code [spinner stopanimating]; here then the indicator does not appear    
}

Answer 1

问题是您尝试启动微调器，从 Internet 加载数据，然后停止主线程上的微调器，并且所有操作都在同一方法中。在主线程上进行同步网络是不好的。

您需要启动微调器，然后在后台执行网络访问。完成此操作后，您将停止主线程上的微调器。

GCD对此非常好。像这样：

- (void)clickToGetLocation {
    spinner = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(0,100, 20, 20)];
    [spinner setActivityIndicatorViewStyle:UIActivityIndicatorViewStyleGray];
    [self.view addSubview:spinner]; 
    [spinner startAnimating];
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        AppDelegate *delegate=(AppDelegate *)[[UIApplication sharedApplication]delegate];
        NSString *urlString = [NSString stringWithFormat:@"http://maps.google.com/maps/geo?q=%f,%f&output=csv",delegate.latitude, delegate.longitude];
        NSError* error;
        NSString *locationString = [NSString stringWithContentsOfURL:[NSURL URLWithString:urlString] encoding:NSASCIIStringEncoding error:&error];
        NSLog(@"%@",locationString);
        locationString = [locationString stringByReplacingOccurrencesOfString:@""" withString:@""];
        dispatch_async(dispatch_get_main_queue(), ^{
            self.loctxt.text = [locationString substringFromIndex:6];
            [spinner stopAnimating];
        });
    });
}

Answer 2

你可以试试这个spinner.hidesWhenStopped = YES