Question

如何在以下代码中将usleep替换为NSTimer：

/**
 * DETERMINATE BAR with LABEL
 */

- (void)showDeterminateBarWithLabel:(CDVInvokedUrlCommand *)command {

    // obtain commands
    bool dim = [[command.arguments objectAtIndex:0] boolValue];
    int increment = [[command.arguments objectAtIndex:1] intValue];
    NSNumber* incrementValue = @(increment);
    NSString* text = [command.arguments objectAtIndex:2];

    // initialize indicator with options, text, detail
    self.progressIndicator = nil;
    self.progressIndicator = [MBProgressHUD showHUDAddedTo:self.webView.superview animated:YES];
    self.progressIndicator.mode = MBProgressHUDModeDeterminateHorizontalBar;
    self.progressIndicator.labelText = text;


    // Check for dim : true ? false
    if (dim == true) {
        self.progressIndicator.dimBackground = YES;
    }

    // Load Progress bar with ::incrementValue
    [self.progressIndicator showWhileExecuting:@selector(progressTask:) onTarget:self withObject:incrementValue animated:YES];

    CDVPluginResult* pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_OK messageAsString:@""];
    [self.commandDelegate sendPluginResult:pluginResult callbackId:command.callbackId];
}

- (void)progressTask:(NSNumber *)increment{

    // get increment value
    int _increment = [increment intValue];

    float progress = 0.0f;
    while (progress < 1.0f) {
        progress += 0.01f;
        self.progressIndicator.progress = progress;

        // increment in microseconds (100000mms = 1s)
        usleep(_increment);
    }
}

此代码取自here。

Answer 1

简而言之，您无法使用阻止线程。使用任何类型的睡眠或延迟来阻塞线程是一种糟糕的设计，应该在极少数情况下避免使用。

严禁在iOS / OS X应用程序中阻止主线程。必须允许主runloop运行，否则你的应用程序最多会没有响应，最坏的情况是不行。

相反，使用NSTimer定期回调代码以更新值。它不会阻止执行。

用NSTimer替换usleep？

1 个答案: