networkActivityIndicatorVisible [英] networkActivityIndicatorVisible
问题描述
此代码与networkActivityIndicatorVisible一起使用是否正确?
Is this code correct to use with the networkActivityIndicatorVisible?
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
UIApplication* app2 = [UIApplication sharedApplication];
app2.networkActivityIndicatorVisible = YES;
[self loadSources]; // Loads data in table view
app2.networkActivityIndicatorVisible = NO;
}
Teo
推荐答案
由于 NetworkActivityIndicatorVisible
可以在连接仍处于活动状态时从多个点设置,因此您需要跟踪启用/禁用的呼叫数量它。以下 UIApplication
类别仅使用静态变量:
Since NetworkActivityIndicatorVisible
can be set from several points while a connection is still active, you need to track the number of calls that enable/disable it. The following UIApplication
category does just that using a static variable:
// file UIApplication+NetworkActivity.h
@interface UIApplication (NetworkActivity)
- (void)showNetworkActivityIndicator;
- (void)hideNetworkActivityIndicator;
@end
// file UIApplication+NetworkActivity.m
#import "UIApplication+NetworkActivity.h"
static NSInteger activityCount = 0;
@implementation UIApplication (NetworkActivity)
- (void)showNetworkActivityIndicator {
if ([[UIApplication sharedApplication] isStatusBarHidden]) return;
@synchronized ([UIApplication sharedApplication]) {
if (activityCount == 0) {
[self setNetworkActivityIndicatorVisible:YES];
}
activityCount++;
}
}
- (void)hideNetworkActivityIndicator {
if ([[UIApplication sharedApplication] isStatusBarHidden]) return;
@synchronized ([UIApplication sharedApplication]) {
activityCount--;
if (activityCount <= 0) {
[self setNetworkActivityIndicatorVisible:NO];
activityCount=0;
}
}
}
@end
现在在您的客户端代码中导入 UIApplication + NetworkActivity.h
并致电
Now import UIApplication+NetworkActivity.h
in your client code and call
// on connection started:
[[UIApplication sharedApplication] showNetworkActivityIndicator];
// on connection finished:
[[UIApplication sharedApplication] hideNetworkActivityIndicator];
如果您担心指标只闪烁一秒钟,则不需要后台处理。只需调用 [self performSelector:@selector(loadSources)withObject:Nil afterDelay:0.1]
,这样UI线程就有时间在阻止主线程之前启动网络指示器动画。
If your concern is that the indicator blinks for only a second, you don't need a background process. Just call [self performSelector:@selector(loadSources) withObject:Nil afterDelay:0.1]
so the UI thread has time to start the network indicator animation before you block the main thread.
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