UIActivityIndi​​catorView没有停止

Question

我是iOS开发的新手。今天我学到了什么是UIActivityIndi​​catorView。 现在，我正在构建一个项目，我有一个表视图，我已经使用JSON解析填充了表。现在我添加了一个活动指示器，它将旋转到那个时间，直到表格填充为止。 我已经启动了活动指示器，但它没有停止。你能告诉我我哪里错了吗？提前致谢。 这是我的代码。

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self fetchData];
self.mySpinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
_mySpinner.hidden = NO;

}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

- (void) fetchData  {

[_mySpinner startAnimating];

NSString *strURL = [NSString stringWithFormat:@"http://api.kivaws.org/v1/loans/search.json?status=fundraising"];
NSURL *url = [NSURL URLWithString:strURL];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:request delegate:self];
if (conn) {
    _webData = [NSMutableData data];
}
else{
    //error
}

}

#pragma mark Url connection Delegate

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
// A response has been received, this is where we initialize the instance var you created
// so that we can append data to it in the didReceiveData method
// Furthermore, this method is called each time there is a redirect so reinitializing it
// also serves to clear it
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
// Append the new data to the instance variable you declared
[_webData appendData:data];

}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {

// The request is complete and data has been received
// You can parse the stuff in your instance variable now
// self.data parse

NSDictionary *dict= [NSJSONSerialization JSONObjectWithData:self.webData options:kNilOptions error:nil];
self.arrDetail = [dict valueForKey:@"loans"];

[self.mySpinner stopAnimating];
self.mySpinner.hidden = YES;

[self.parserTable reloadData];

}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
// The request has failed for some reason!
// Check the error var

}

#pragma mark Table View Delegates


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];


NSDictionary *locationDict = [[self.arrDetail objectAtIndex:indexPath.row]valueForKey:@"location"];

UILabel *lbl1 = (UILabel*)[cell.contentView viewWithTag:1];
lbl1.text = [[self.arrDetail objectAtIndex:indexPath.row]valueForKey:@"name"];

UILabel *lbl2 = (UILabel*)[cell.contentView viewWithTag:2];
lbl2.text = [locationDict valueForKey:@"country"];


return cell;

}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{

return [self.arrDetail count];

}


@end

Answer 1

解决方案

从代码中删除此行

self.mySpinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite]

问题

您尚未显示mySpinner的声明声明。但是，从您的代码中我可以看出它是一个IBOutlet，因为您创建了一个UIActivityIndicatorView的新实例而没有将其添加为子视图，您仍然可以在视图中看到一个活动指示器（因为它出现并且永不停止动画）。

它不会停止动画的原因是您在IBOutlet上调用[_mySpinner startAnimating];。然后在您说

时创建UIActivityIndicatorView的新实例

self.mySpinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite]

现在，您在mySpinner上调用的任何方法都会在一个活动指示符上调用，该指标不在您的视图中，而是您创建的那个，因为您在创建新{{1}时失去了对它的引用}。

另外，既然你是新人。我建议您尽可能使用UIActivityIndicatorView，不要互换使用self.mySpinner和self，因为两者都可以根据需要使用。原因超出了你的问题的范围。

Answer 2

启动活动指示器：

[cell.indicater startAnimating];

启动活动指示器：

[cell.indicater stopAnimating];

还设置截图中显示的属性。

Answer 3

由于您要为您的outlet属性分配UIActivityIndicatorView的新实例，因此对InterfaceBuilder中的一个实例的引用将丢失。

只需删除：self.mySpinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];

Answer 4

首先初始化您的微调器，然后调用您的连接方法，如下所示。

...

- (void)viewDidLoad {
    [super viewDidLoad];
    self.mySpinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
    _mySpinner.hidden = NO;
    _mySpinner.center = self.view.center;
    [self fetchData];
}

...