如何检查CLLocationCoordinate2D是否在四个CLLocationCoordinate2D广场内？目标C中的Google
如何检查CLLocationCoordinate2D是否在四个CLLocationCoordinate2D广场内？目标C中的Google
提问于 2015-05-25 07:18:17
我想测试一个CLLocationCoordinate2D是否在由其他四个CLLocationCoordinate2D创建的正方形中
我有这样的结构：
typedef struct {
CLLocationCoordinate2D southWest;
CLLocationCoordinate2D southEast;
CLLocationCoordinate2D northEast;
CLLocationCoordinate2D northWest;
} Bounds;并将CLLocationCoordinate2D坐标作为param传递。我想测试坐标是否在边界内。我该怎么测试呢？
- (BOOL) isCoordinate:(CLLocationCoordinate2D)coordinate insideBounds:(Bounds)bounds { ... }回答 3
Stack Overflow用户
回答已采纳
发布于 2015-05-25 08:36:52
如果您有四点，您可以创建一个CGRect并使用CGRectContainsPoint()
Stack Overflow用户
发布于 2015-05-25 08:20:56
您只需创建一个CLregion或CLCircularRegion并检查坐标是否包含在该区域内.
像这样
CLCircularRegion *myRegion = [[CLCircularRegion alloc] initWithCenter:CLLocationCoordinate2DMake(22, -111) radius:500 identifier:@"myRegion"];
if ([myRegion containsCoordinate:CLLocationCoordinate2DMake(22.45, -111.1)]) {
//Do what you want here
}Stack Overflow用户
发布于 2015-05-25 09:01:11
如果这4个点不代表矩形或圆形，而是地图上的任意4个点，那么您需要自己创建系统。对于一个由4个定向点表示的形状内的点，最容易检查中心和每一对连续的边界点之间的交叉积。所有的结果必须是积极的时钟为点在边界内的顺序。第二件事是你需要把坐标转换成笛卡儿系统并给它们定位.让代码本身来说明：
- (double)crossProductZCoordinateForCenter:(CLLocationCoordinate2D)center left:(CLLocationCoordinate2D)left right:(CLLocationCoordinate2D)right {
CLLocationCoordinate2D A = CLLocationCoordinate2DMake(left.latitude-center.latitude, left.longitude-center.longitude);
CLLocationCoordinate2D B = CLLocationCoordinate2DMake(right.latitude-center.latitude, right.longitude-center.longitude);
return B.latitude*A.longitude - A.latitude*B.longitude;
}
- (BOOL)isCartesianCoordinate:(CLLocationCoordinate2D)coordinate insideBounds:(Bounds)bounds {
// Now we will break the system into 4 triangles and check their orientation by using a z component of the cross product. If one of them if negative the coordinate is not inside the region
if([self crossProductZCoordinateForCenter:coordinate left:bounds.southWest right:bounds.northWest] < .0) return NO;
if([self crossProductZCoordinateForCenter:coordinate left:bounds.northWest right:bounds.northEast] < .0) return NO;
if([self crossProductZCoordinateForCenter:coordinate left:bounds.northEast right:bounds.southEast] < .0) return NO;
if([self crossProductZCoordinateForCenter:coordinate left:bounds.southEast right:bounds.southWest] < .0) return NO;
return YES;
}
- (BOOL)isCoordinate:(CLLocationCoordinate2D)coordinate insideBounds:(Bounds)bounds {
// We may treat the coordinates as cartesian but east should always be larger then west and north should be larger then south
// Those smaller must be increased by 360 degrees
if(bounds.southEast.latitude < bounds.southWest.latitude) bounds.southEast.latitude += 360.0;
if(bounds.northEast.latitude < bounds.northWest.latitude) bounds.northEast.latitude += 360.0;
if(bounds.northEast.longitude < bounds.southEast.longitude) bounds.northEast.longitude += 360.0;
if(bounds.northWest.longitude < bounds.southWest.longitude) bounds.northWest.longitude += 360.0;
// Check if any of the combination coordinates are cartesicly inside the bounds
// We need to increase the longitude and the latitude by 360 and check all 4 combinations
if([self isCartesianCoordinate:coordinate insideBounds:bounds]) return YES;
if([self isCartesianCoordinate:CLLocationCoordinate2DMake(coordinate.latitude+360.0, coordinate.longitude) insideBounds:bounds]) return YES;
if([self isCartesianCoordinate:CLLocationCoordinate2DMake(coordinate.latitude, coordinate.longitude+360.0) insideBounds:bounds]) return YES;
if([self isCartesianCoordinate:CLLocationCoordinate2DMake(coordinate.latitude+360.0, coordinate.longitude+360.0) insideBounds:bounds]) return YES;
return NO;
}一些简单的测试可能会派上用场：
- (void)resampleCoordinate:(CLLocationCoordinate2D *)coordinate {
if(coordinate->latitude < -180.0) coordinate->latitude += 360.0;
if(coordinate->latitude > 180.0) coordinate->latitude -= 360.0;
if(coordinate->longitude < -180.0) coordinate->longitude += 360.0;
if(coordinate->longitude > 180.0) coordinate->longitude -= 360.0;
}
- (void)testLocationSystem {
NSInteger numberOfTests = 0;
NSInteger numberOfTestsCheckedOut = 0;
for(double latitude = -180.0; latitude <= 180.0; latitude++) {
for(double longitude = -180.0; longitude <= 180.0; longitude++) {
Bounds bounds;
bounds.southWest = CLLocationCoordinate2DMake(latitude-15.0, longitude-15.0);
bounds.northEast = CLLocationCoordinate2DMake(latitude+15.0, longitude+15.0);
bounds.northWest = CLLocationCoordinate2DMake(latitude-15.0, longitude+15.0);
bounds.southEast = CLLocationCoordinate2DMake(latitude+15.0, longitude-15.0);
[self resampleCoordinate:&(bounds.northWest)];
[self resampleCoordinate:&(bounds.northEast)];
[self resampleCoordinate:&(bounds.southEast)];
[self resampleCoordinate:&(bounds.southWest)];
numberOfTests++;
BOOL success = [self isCoordinate:CLLocationCoordinate2DMake(latitude, longitude) insideBounds:bounds];
if(success) {
numberOfTestsCheckedOut++;
}
else {
NSLog(@"Failed");
}
}
}
NSLog(@"%d/%d succeeded", (int)numberOfTestsCheckedOut, (int)numberOfTests);
}
- (void)testLocationFailSystem {
NSInteger numberOfTests = 0;
NSInteger numberOfTestsCheckedOut = 0;
for(double latitude = -180.0; latitude <= 180.0; latitude++) {
for(double longitude = -180.0; longitude <= 180.0; longitude++) {
Bounds bounds;
bounds.southWest = CLLocationCoordinate2DMake(latitude-15.0, longitude-15.0);
bounds.northEast = CLLocationCoordinate2DMake(latitude+15.0, longitude+15.0);
bounds.northWest = CLLocationCoordinate2DMake(latitude-15.0, longitude+15.0);
bounds.southEast = CLLocationCoordinate2DMake(latitude+15.0, longitude-15.0);
[self resampleCoordinate:&(bounds.northWest)];
[self resampleCoordinate:&(bounds.northEast)];
[self resampleCoordinate:&(bounds.southEast)];
[self resampleCoordinate:&(bounds.southWest)];
for(double angle = .0f; angle < M_PI; angle+=M_PI/10.0) {
CLLocationCoordinate2D coordiunate = CLLocationCoordinate2DMake(latitude+cos(angle)*20.0, longitude+sin(angle)*20.0);
[self resampleCoordinate:&coordiunate];
numberOfTests++;
BOOL success = [self isCoordinate:coordiunate insideBounds:bounds]; // must fail
if(success == NO) {
numberOfTestsCheckedOut++;
}
else {
NSLog(@"Failed");
}
}
}
}
NSLog(@"%d/%d succeeded", (int)numberOfTestsCheckedOut, (int)numberOfTests);
}这些都是我的通行证。如果你发现情况不工作，但应该或其他方式，请联系我。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/30433076
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