动画雷达覆盖 MKMapView iOS

Question

我正在从当前天气雷达的 NOAA 获取 gif，我将其存储在 UIImage 中，然后将其绘制到 MKMapView，这是我正在使用的一些代码：

image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://radar.weather.gov/ridge/Conus/RadarImg/latest_radaronly.gif"]]];

MKMapRect theMapRect    = [self.overlay boundingMapRect];
CGRect theRect           = [self rectForMapRect:theMapRect];

@try {
    UIGraphicsBeginImageContext(image.size);
    UIGraphicsPushContext(ctx);
    [image drawInRect:theRect];
    UIGraphicsPopContext();
    UIGraphicsEndImageContext();
}
@catch (NSException *exception) {
    NSLog(@"Caught an exception while drawing radar on map - %@",[exception description]);
}
@finally {

}

有谁知道我可以如何反复制作此 gif 动画，以实现您在新闻中看到的类似雷达的天气。我找到了几个可以做到这一点的应用程序，我想知道如何将它整合到我自己的项目中。

Answer 1

您提供的链接实际上并未显示动画 gif。它只是检索最新的 gif。一种方法是加载 NOAA 上传的最新 10-20 gif here，他们似乎每 10 分钟更新一次，然后为每个 gif 创建一个 UIImage 并在 UIImageview 中循环浏览它们覆盖您的地图。 例如：

// Set images
radarGIF01 = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://radar.weather.gov/ridge/Conus/RadarImg/Conus_20150209_0108_N0Ronly.gif"]]];
radarGIF02 = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://radar.weather.gov/ridge/Conus/RadarImg/Conus_20150209_0118_N0Ronly.gif"]]];
radarGIF03 = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://radar.weather.gov/ridge/Conus/RadarImg/Conus_20150209_0128_N0Ronly.gif"]]];
radarGIF04 = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://radar.weather.gov/ridge/Conus/RadarImg/Conus_20150209_0138_N0Ronly.gif"]]];
radarGIF05 = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://radar.weather.gov/ridge/Conus/RadarImg/Conus_20150209_0148_N0Ronly.gif"]]];

// Add images to array
radarImagesArray = [[NSArray alloc]initWithObjects: radarGIF01, radarGIF02, radarGIF03, radarGIF04, radarGIF05, nil];

// Animate images in UIImageview
_radarImageView.animationImages = radarImagesArray;
_radarImageView.animationDuration = 3.0;
_radarImageView.animationRepeatCount = 0;
[_radarImageView startAnimating];