我的应用程序中有一个方形MKMapView，我希望设置一个中心点和视图的精确高度/宽度（以米为单位）。
创建MKCoordinateRegion并将地图设置为该区域（如本代码所示…
MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(center_coord, 1000.0, 1000.0);
[self.mapView setRegion:region animated:YES];
..）不能正常工作，因为在这里使用区域只意味着至少显示该区域，通常比显示的区域更多
我计划使用setVisibleMapRect:animation:方法，因为我相信这将缩放到传递的实际MKMapRect。
那么，有没有一种简单的方法可以在MKcoordinateRegion和MKMapRect之间进行转换？也许可以获得该区域的左上角和右下角坐标，并使用它们来制作MKMapRect
我在地图套件功能参考中看不到任何方便的东西。
（使用iOS 5，Xcode 4.2）
向堆中添加另一个实现：
- (MKMapRect)MKMapRectForCoordinateRegion:(MKCoordinateRegion)region
{
MKMapPoint a = MKMapPointForCoordinate(CLLocationCoordinate2DMake(
region.center.latitude + region.span.latitudeDelta / 2,
region.center.longitude - region.span.longitudeDelta / 2));
MKMapPoint b = MKMapPointForCoordinate(CLLocationCoordinate2DMake(
region.center.latitude - region.span.latitudeDelta / 2,
region.center.longitude + region.span.longitudeDelta / 2));
return MKMapRectMake(MIN(a.x,b.x), MIN(a.y,b.y), ABS(a.x-b.x), ABS(a.y-b.y));
}
注意：MKMapRect和MKCoordinateRegion之间有很多转换方式。这个肯定是而不是MKCoordinateRegionMakeWithDistance()的精确逆，但相当好地近似了它。因此，要小心来回转换，因为信息可能会丢失。
这是Leo&Barnhart解决方案
func MKMapRectForCoordinateRegion(region:MKCoordinateRegion) -> MKMapRect {
let topLeft = CLLocationCoordinate2D(latitude: region.center.latitude + (region.span.latitudeDelta/2), longitude: region.center.longitude - (region.span.longitudeDelta/2))
let bottomRight = CLLocationCoordinate2D(latitude: region.center.latitude - (region.span.latitudeDelta/2), longitude: region.center.longitude + (region.span.longitudeDelta/2))
let a = MKMapPoint(topLeft)
let b = MKMapPoint(bottomRight)
return MKMapRect(origin: MKMapPoint(x:min(a.x,b.x), y:min(a.y,b.y)), size: MKMapSize(width: abs(a.x-b.x), height: abs(a.y-b.y)))
}
使用MKMapPointForCoordinate转换区域的2个点（上/左和下/右），然后使用2个MKMapPoints 创建MKMapRect
CLLocationCoordinate2D coordinateOrigin = CLLocationCoordinate2DMake(latitude, longitude);
CLLocationCoordinate2D coordinateMax = CLLocationCoordinate2DMake(latitude + cellSize, longitude + cellSize);
MKMapPoint upperLeft = MKMapPointForCoordinate(coordinateOrigin);
MKMapPoint lowerRight = MKMapPointForCoordinate(coordinateMax);
MKMapRect mapRect = MKMapRectMake(upperLeft.x,
upperLeft.y,
lowerRight.x - upperLeft.x,
lowerRight.y - upperLeft.y);
您可以使用方法将MKCoordinateRegion转换为CGRect
- (CGRect)convertRegion:(MKCoordinateRegion)region toRectToView:(UIView *)view
并使用- (MKMapRect)mapRectForRect:(CGRect)rect
或者使用MKMapPointForCoordinate方法首先将坐标转换为MKPoint，然后使用该方法形成MKMapRect，最终使用setVisibleMapRect:animated:
@Bogdan
我认为应该是：
CLLocationCoordinate2D topLeftCoordinate =
CLLocationCoordinate2DMake(coordinateRegion.center.latitude
+ (coordinateRegion.span.latitudeDelta/2.0),
coordinateRegion.center.longitude
- (coordinateRegion.span.longitudeDelta/2.0));
MKMapPoint topLeftMapPoint = MKMapPointForCoordinate(topLeftCoordinate);
CLLocationCoordinate2D bottomRightCoordinate =
CLLocationCoordinate2DMake(coordinateRegion.center.latitude
- (coordinateRegion.span.latitudeDelta/2.0),
coordinateRegion.center.longitude
+ (coordinateRegion.span.longitudeDelta/2.0));
MKMapPoint bottomRightMapPoint = MKMapPointForCoordinate(bottomRightCoordinate);
MKMapRect mapRect = MKMapRectMake(topLeftMapPoint.x,
topLeftMapPoint.y,
fabs(bottomRightMapPoint.x-topLeftMapPoint.x),
fabs(bottomRightMapPoint.y-topLeftMapPoint.y));
根据apple api参考，MKCoordinateRegion.center表示区域的中心点；MKCoordinateSpan.latitudeDelta表示要在地图上显示的南北距离（以度为单位）；MKCoordinateSpan.longitudeDelta表示要为地图区域显示的东西距离（以度为单位）。
在穿越子午线（以及绕极）时仍然需要更加小心，否则MKMapPointForCoordinate将返回-1，-1:
public func MKMapRectForCoordinateRegion(region:MKCoordinateRegion) -> MKMapRect {
var topLeft = CLLocationCoordinate2D(
latitude: min(region.center.latitude + (region.span.latitudeDelta/2.0), 90),
longitude: region.center.longitude - (region.span.longitudeDelta/2.0)
)
if topLeft.longitude < -180 {
// We wrapped around the meridian
topLeft.longitude += 360
}
var bottomRight = CLLocationCoordinate2D(
latitude: max(region.center.latitude - (region.span.latitudeDelta/2.0), -90),
longitude: region.center.longitude + (region.span.longitudeDelta/2.0)
)
if bottomRight.longitude > 180 {
// We wrapped around the medridian
bottomRight.longitude -= 360
}
let topLeftMapPoint = MKMapPointForCoordinate(topLeft)
let bottomRightMapPoint = MKMapPointForCoordinate(bottomRight)
var width = bottomRightMapPoint.x - topLeftMapPoint.x
if width < 0.0 {
// Rect crosses meridian
width += MKMapPointForCoordinate(CLLocationCoordinate2D(latitude: 0.0, longitude: 180.0)).x
}
let height = bottomRightMapPoint.y - topLeftMapPoint.y
let size = MKMapSize(width: width, height: height)
return MKMapRect(origin: topLeftMapPoint, size: size)
}
一些测试用例代码（使用Nimble）：
func testMKMapRectForCoordinateRegion() {
let northWesternRegion = MKCoordinateRegionMake(CLLocationCoordinate2DMake(45.0, -90.0), MKCoordinateSpanMake(20.0, 20.0))
let northWesternMapRect = MKMapRectForCoordinateRegion(region: northWesternRegion)
let convertedNWRegion = MKCoordinateRegionForMapRect(northWesternMapRect)
expect(self.equivalentRegions(northWesternRegion, convertedNWRegion)).to(beTrue())
let northEasternRegion = MKCoordinateRegionMake(CLLocationCoordinate2DMake(45.0, 90.0), MKCoordinateSpanMake(20.0, 20.0))
let northEasternMapRect = MKMapRectForCoordinateRegion(region: northEasternRegion)
let convertedNERegion = MKCoordinateRegionForMapRect(northEasternMapRect)
expect(self.equivalentRegions(northEasternRegion, convertedNERegion)).to(beTrue())
let southWesternRegion = MKCoordinateRegionMake(CLLocationCoordinate2DMake(-45.0, -90.0), MKCoordinateSpanMake(20.0, 20.0))
let southWesternMapRect = MKMapRectForCoordinateRegion(region: southWesternRegion)
let convertedSWRegion = MKCoordinateRegionForMapRect(southWesternMapRect)
expect(self.equivalentRegions(southWesternRegion, convertedSWRegion)).to(beTrue())
let southEasternRegion = MKCoordinateRegionMake(CLLocationCoordinate2DMake(-45.0, 90.0), MKCoordinateSpanMake(20.0, 20.0))
let southEasternMapRect = MKMapRectForCoordinateRegion(region: southEasternRegion)
let convertedSERegion = MKCoordinateRegionForMapRect(southEasternMapRect)
expect(self.equivalentRegions(southEasternRegion, convertedSERegion)).to(beTrue())
let meridianSpanEastRegion = MKCoordinateRegionMake(CLLocationCoordinate2DMake(0.0, 170.0), MKCoordinateSpanMake(20.0, 20.0))
let meridianSpanEastMapRect = MKMapRectForCoordinateRegion(region: meridianSpanEastRegion)
let convertedMeridianSpanEastRegion = MKCoordinateRegionForMapRect(meridianSpanEastMapRect)
expect(self.equivalentRegions(meridianSpanEastRegion, convertedMeridianSpanEastRegion)).to(beTrue())
let meridianSpanWestRegion = MKCoordinateRegionMake(CLLocationCoordinate2DMake(0.0, -170.0), MKCoordinateSpanMake(20.0, 20.0))
let meridianSpanWestMapRect = MKMapRectForCoordinateRegion(region: meridianSpanWestRegion)
let convertedMeridianSpanWestRegion = MKCoordinateRegionForMapRect(meridianSpanWestMapRect)
expect(self.equivalentRegions(meridianSpanWestRegion, convertedMeridianSpanWestRegion)).to(beTrue())
}
fileprivate func equivalentRegions(_ regionA: MKCoordinateRegion, _ regionB: MKCoordinateRegion) -> Bool {
// Allow a small delta between values
let deltaAllowed: Double = 1.0
return (fabs(regionA.center.latitude - regionB.center.latitude) < deltaAllowed) &&
(fabs(regionA.center.longitude - regionB.center.longitude) < deltaAllowed) &&
(fabs(regionA.span.latitudeDelta - regionB.span.latitudeDelta) < deltaAllowed) &&
(fabs(regionA.span.longitudeDelta - regionB.span.longitudeDelta) < deltaAllowed)
}
@David给出的答案（以及@onmyway133的Swift 3版本）在该区域从东半球（经度0度到180度）到西半球（经度-180度到0度）的反子午线上交叉时都会出现重大错误。MKMapRect的宽度将大于其应有的宽度（通常大很多）。
以下是修复（针对Swift 3代码）：
let topLeftMapPoint = MKMapPointForCoordinate(topLeft)
let bottomRightMapPoint = MKMapPointForCoordinate(bottomRight)
var width = bottomRightMapPoint.x - topLeftMapPoint.x
if width < 0.0 {
// Rect crosses from the Eastern Hemisphere to the Western Hemisphere
width += MKMapPointForCoordinate(CLLocationCoordinate2D(latitude: 0.0, longitude: 180.0)).x
}
let height = bottomRightMapPoint.y - topLeftMapPoint.y
let size = MKMapSize(width: width, height: height)
return MKMapRect(origin: topLeftMapPoint, size: size)
取一个MKCoordinateRegion，用上面的代码将其转换为MKMapRect，然后使用MKCoordinationRegionForMapRect（）将其转换回MKCoordiniteRegion。这使我在地图上的输入区域和输出区域之间达成了非常好的一致性。
@David的答案，Swift 3
func mapRect(region: MKCoordinateRegion) -> MKMapRect {
let topLeft = CLLocationCoordinate2D(
latitude: region.center.latitude + (region.span.latitudeDelta/2.0),
longitude: region.center.longitude - (region.span.longitudeDelta/2.0)
)
let bottomRight = CLLocationCoordinate2D(
latitude: region.center.latitude - (region.span.latitudeDelta/2.0),
longitude: region.center.longitude + (region.span.longitudeDelta/2.0)
)
let topLeftMapPoint = MKMapPointForCoordinate(topLeft)
let bottomRightMapPoint = MKMapPointForCoordinate(bottomRight)
let origin = MKMapPoint(x: topLeftMapPoint.x,
y: topLeftMapPoint.y)
let size = MKMapSize(width: fabs(bottomRightMapPoint.x - topLeftMapPoint.x),
height: fabs(bottomRightMapPoint.y - topLeftMapPoint.y))
return MKMapRect(origin: origin, size: size)
}
Swift 5.1:
func mapRectForCoordinateRegion(_ region: MKCoordinateRegion) -> MKMapRect {
let topLeftCoordinate = CLLocationCoordinate2DMake(region.center.latitude + (region.span.latitudeDelta / 2.0), region.center.longitude - (region.span.longitudeDelta / 2.0))
let topLeftMapPoint = MKMapPoint(topLeftCoordinate)
let bottomRightCoordinate = CLLocationCoordinate2DMake(region.center.latitude - (region.span.latitudeDelta / 2.0), region.center.longitude + (region.span.longitudeDelta / 2.0))
let bottomRightMapPoint = MKMapPoint(bottomRightCoordinate)
return MKMapRect(x: topLeftMapPoint.x, y: topLeftMapPoint.y, width: fabs(bottomRightMapPoint.x - topLeftMapPoint.x), height: fabs(bottomRightMapPoint.y - topLeftMapPoint.y))
}
由于扩展规则，这里有一个swift的扩展：
extension MKCoordinateRegion {
public var rect : MKMapRect {
let topLeft = CLLocationCoordinate2D(latitude: self.center.latitude + (self.span.latitudeDelta/2), longitude: self.center.longitude - (self.span.longitudeDelta/2))
let bottomRight = CLLocationCoordinate2D(latitude: self.center.latitude - (self.span.latitudeDelta/2), longitude: self.center.longitude + (self.span.longitudeDelta/2))
let a = MKMapPoint(topLeft)
let b = MKMapPoint(bottomRight)
return MKMapRect(origin: MKMapPoint(x:min(a.x,b.x), y:min(a.y,b.y)), size: MKMapSize(width: abs(a.x-b.x), height: abs(a.y-b.y)))
}
}
这允许：region.rect只工作：）
使用内置函数MKCoordinateRegionForMapRect
MKCoordinateRegion region = MKCoordinateRegionForMapRect(rect);