ios - 如何暂停我的应用程序足够长的时间以使我的屏幕显示为 "catch up"

Question

我正在做一个同步网络请求，我想显示进度，但更重要的是，只要我点击“开始”，它就会开始比赛，忽略诸如打开 NetworkActivty 微调器或更改标签之类的事情.

我意识到进度条可能必须等到我有时间异步写入提取，但我可以让程序等到标签发生变化吗？或者至少是一种伪造它的方法？

在我拥有的 UIButton 上的 TouchUpInside 上。 . .

-(IBAction)startButtonPressed

{ [UIApplication sharedApplication].networkActivityIndi​​catorVisible = YES;

NSString *lastUpdate = [[self getLastUpdateDate] stringByReplacingOccurrencesOfString:@" " withString:@"%20"];
startButton.enabled = NO;
cancelButton.enabled = NO;
resetSwitch.enabled = NO;
cleanSwitch.enabled = NO;
//check the # of customer updates and update accordingly

statusLabel.text = @"Updating Customers. . .";
//[self performSelector:(@selector(updateProgress:withStatus:)) withObject:0.0f withObject:@"Updating Customers. . . " afterDelay:500];
//[self performSelector:(@selector(updateProgressIndicators)) withObject:nil afterDelay:0];

if (clean) {
    [self deleteALL];
}

if ([self customersCount] < 1000 && !reset)
    [self addCustomers:lastUpdate];
else
    [self addCustomers:nil];

//check the # of product updates and update accordingly, reset does not affect products
statusLabel.text = @"Updating Products. . .";

if ([self productsCount] < 25000 || !clean)
    [self addProducts:lastUpdate];
else
    [self addProducts:nil];

//check the # of vendor updates and update accordingly, reset does not affect vendors
statusLabel.text = @"Updating Vendors. . . ";
if ([self vendorsCount] < 1000 || !clean || [[self fetchVendor:@"0002"] count] == 0) {
    [self addVendors:lastUpdate];
}else{
    [self addVendors:nil];
}

statusLabel.text = @"Updating History. . . ";
[self getHistory];



statusLabel.text = @"Updating Custom Pricing. . . ";
if ([self customPricesCount] < 500 && !reset) {
    [self addCustomPrices:lastUpdate];
}else{
    [self addCustomPrices:nil];
}

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"MM-dd-yyyy HH:mm:ss"];
[self setLastUpdateDate:[dateFormatter stringFromDate:[NSDate date]]];  
[dateFormatter release];

statusLabel.text = @"Done!";
cancelButton.enabled = YES;
cancelButton.tag = 1;
cancelButton.titleLabel.text = @"Close";
startButton.enabled = NO;

[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
}

Answer 1

您有一种可能性是安排网络请求在主线程上执行。这将允许 UI 在发送网络请求之前得到更新。

为了做到这一点，您应该将代码分成两种方法:

1. UI变化(activity indicator等)直到同步网络请求；

2. 同步网络请求和响应处理(UI 更新)；

假设 2. 是由一个名为 offToTheRaces 的方法实现的，您将从第一个方法开始安排此方法:

[self performSelector:@selector(offToTheRaces) withObject:nil afterDelay:0];

请注意，您没有以这种方式进行任何类型的多线程处理，也没有引入延迟。您只需安排在主循环再次执行后执行的方法，这将为 tue UI 提供更新的机会。