How to show the loading indicator in the top statu

问题:

I have noticed that some apps like Safari and Mail show a loading indicator in the status bar (the bar at the very top of the phone) when they are accessing the network. Is there a way to do the same thing in SDK apps, or is this an Apple only thing?

回答1:

It's in UIApplication:

For Objective C:

Start:

[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

End:

[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;

For swift :

Start

UIApplication.shared.isNetworkActivityIndicatorVisible = true

End

UIApplication.shared.isNetworkActivityIndicatorVisible = false

回答2:

I've found the following macros pretty useful!

#define ShowNetworkActivityIndicator() [UIApplication sharedApplication].networkActivityIndicatorVisible = YES
#define HideNetworkActivityIndicator() [UIApplication sharedApplication].networkActivityIndicatorVisible = NO

So you can just call ShowNetworkActivityIndicator(); or HideNetworkActivityIndicator(); from within your app (as long as the header is included of course!).

回答3:

I wrote a singleton that solves the problem of multiple connections by keeping a counter of what is happening (to avoid removing the status when a connection returns but another one is still active):

The header file:

#import <Foundation/Foundation.h>

@interface RMActivityIndicator : NSObject

-(void)increaseActivity;
-(void)decreaseActivity;
-(void)noActivity;

+(RMActivityIndicator *)sharedManager;

@end

and implementation:

#import "RMActivityIndicator.h"

@interface RMActivityIndicator ()

@property(nonatomic,assign) unsigned int activityCounter;

@end

@implementation RMActivityIndicator

- (id)init
{
    self = [super init];
    if (self) {
        self.activityCounter = 0;
    }
    return self;
}

    -(void)increaseActivity{
        @synchronized(self) {
             self.activityCounter++;
        }
        [self updateActivity];
    }
-(void)decreaseActivity{
    @synchronized(self) {
           if (self.activityCounter>0) self.activityCounter--;
    }
    [self updateActivity];
}
-(void)noActivity{
    self.activityCounter = 0;
    [self updateActivity];
}

-(void)updateActivity{
    UIApplication* app = [UIApplication sharedApplication];
    app.networkActivityIndicatorVisible = (self.activityCounter>0);
}

#pragma mark -
#pragma mark Singleton instance

+(RMActivityIndicator *)sharedManager {
    static dispatch_once_t pred;
    static RMActivityIndicator *shared = nil;

    dispatch_once(&pred, ^{
        shared = [[RMActivityIndicator alloc] init];
    });
    return shared;
}

@end

Example:

    [[RMActivityIndicator sharedManager]increaseActivity];
    [NSURLConnection sendAsynchronousRequest:urlRequest queue:self.networkReceiveProcessQueue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error)
    {
        [[RMActivityIndicator sharedManager]decreaseActivity];
    }

回答4:

A single line code to do that:

[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;

回答5:

You need to take care of hiding the activity indicator also once your network call is done.

If you use AFNetworking, then you don't need to do much.

Do following changes in AppDelegate Class:

1. Import AFNetworking/AFNetworkActivityIndicatorManager.h

2. Put this in didFinishLaunchingWithOptions:

[[AFNetworkActivityIndicatorManager sharedManager] setEnabled:YES]

回答6:

The status bar network activity indicator was deprecated in iOS 13.

Using UIApplication.shared.isNetworkActivityIndicatorVisible = true will not work anymore.

The deprecation message says:

Provide a custom network activity UI in your app if desired.

回答7:

It might also be helpful to make sure you are running it on the main thread as it is UI related.

dispatch_async(dispatch_get_main_queue(), ^{
    [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
});

回答8:

As many have said, there is no network activity indicator for the iPhone X and probably for the other new iPhones with the notch.

I came across this incredible library written by Ortwin Gentz, FutureTap: https://github.com/futuretap/FTLinearActivityIndicator

It puts the indicator right back where it was when the iPhone X was initially released, many would remember the Knight Rider type of indicator.

This library is available for Swift 4.2, so you will need to change the Swift Language settings, as described here: Type 'NSAttributedStringKey' (aka 'NSString') has no member 'font'