- (voID)mapVIEw:(GMSMapVIEw *)mapVIEw willMove:(BOol)gesture
以上方法无论动作如何都会发生火灾.
解决方法 还有另一种方法可以检测何时缩放(或任何其他属性)已经改变 – 键值观察(又名KVO).当没有为我们提供的委托方法时,它特别有用.来自Apple docs:Key-value observing provIDes a mechanism that allows objects to be
notifIEd of changes to specific propertIEs of other objects.
无论您在何处设置地图视图,请添加以下代码段:
[self.mapVIEw addobserver:self forKeyPath:@"camera.zoom" options:0 context:nil];
现在你只需要实现-observeValueForKeyPath:ofObject:change:context:实际接收回调的方法.像这样:
- (voID)observeValueForKeyPath:(Nsstring *)keyPath ofObject:(ID)object change:(NSDictionary *)change context:(voID *)context {if ([keyPath isEqualToString:@"camera.zoom"]) { // this static variable will hold the last value between invocations. static CGfloat lastZoom = 0; GMSMapVIEw *mapVIEw = (GMSMapVIEw *)object; CGfloat currentZoom = [[mapVIEw camera] zoom]; if (!(fabs((lastZoom) - (currentZoom)) < FLT_EPSILON)) { //Zoom level has actually changed! NSLog(@"Zoom changed to: %.2f",[[mapVIEw camera] zoom]); } //update last zoom level value. lastZoom = currentZoom; }}
不要忘记根据您的需要删除-dealloc或-vIEwDIDdissapear中的观察者:
- (voID)dealloc { [self.mapVIEw removeObserver:self forKeyPath:@"camera.zoom"];}
快乐的编码:-)
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