iphone – networkActivityIndi??catorVisible

发布时间：2020-12-14 19:00:04 所属栏目：百科来源：网络整理

导读：此代码与networkActivityIndi??catorVisible一起使用是否正确？ - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; UIApplication* app2 = [UIApplication sharedApplication]; app2.networkActivityIndicatorVisible = YES; [self

此代码与networkActivityIndi??catorVisible一起使用是否正确？

- (void)viewWillAppear:(BOOL)animated {

    [super viewWillAppear:animated];

    UIApplication* app2 = [UIApplication sharedApplication]; 
    app2.networkActivityIndicatorVisible = YES; 
    [self loadSources];  // Loads data in table view
    app2.networkActivityIndicatorVisible = NO; 
}

张志贤

解决方法

由于NetworkActivityIndi??catorVisible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/禁用它的调用数.以下UIApplication类别仅使用静态变量：

// 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并调用

// on connection started:
[[UIApplication sharedApplication] showNetworkActivityIndicator];

// on connection finished:
[[UIApplication sharedApplication] hideNetworkActivityIndicator];

如果您担心指示灯只闪烁一秒钟,则不需要后台处理.只需调用[self performSelector：@selector(loadSources)withObject：Nil afterDelay：0.1],这样UI线程就有时间在阻塞主线程之前启动网络指示器动画.

（编辑：李大同）

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