我已经搜索了很多关于这个问题的资料，但是没有一个能完全满足我的需求。许多教程都展示了如何在代码中添加线条和多边形，但没有自由绘制的方法。
问题如下：
我正在构建一个房地产应用程序。如果用户使用MKMapView，则可以绘制一个矩形/圆形等区域，表示他/她想要购买/租赁房屋的区域。然后，我需要显示与用户所选区域对应的结果。
目前，我在MKMapView上方有一个UIView，其中进行一些自定义绘图，有没有一种方式可以从中将点转换为坐标或其他方法？还是完全不能这样做？我也听说过MKMapOverlayView等内容，但不确定如何使用它们。
是否有人能够指导我朝正确的方向前进，或者有一些示例代码或教程可以帮助我完成我需要的工作吗？
谢谢
我有一个应用程序，基本上是这样的。我有一个地图视图，在屏幕顶部有一个工具栏。当您按下该工具栏上的按钮时，您现在处于可以在地图上滑动手指的模式。滑动的起点和终点将表示矩形的角落。应用程序将绘制一个半透明的蓝色矩形覆盖层，以显示您选择的区域。当您放开手指时，矩形选择完成，并且应用程序开始搜索我的数据库中的位置。
我不处理圆形，但我认为您可以做类似的事情，其中您有两种选择模式（矩形或圆形）。在圆形选择模式下，滑动的起点和终点可以表示圆心和边缘（半径）。或者，直径线的两个端点。我会留下那一部分给你。
首先，我定义了一个透明的覆盖层，用于处理选择（OverlaySelectionView.h）：
#import <QuartzCore/QuartzCore.h>
#import <MapKit/MapKit.h>
@protocol OverlaySelectionViewDelegate
// callback when user finishes selecting map region
- (void) areaSelected: (CGRect)screenArea;
@end
@interface OverlaySelectionView : UIView {
@private
UIView* dragArea;
CGRect dragAreaBounds;
id<OverlaySelectionViewDelegate> delegate;
}
@property (nonatomic, assign) id<OverlaySelectionViewDelegate> delegate;
@end
以及OverlaySelectionView.m文件：
#import "OverlaySelectionView.h"
@interface OverlaySelectionView()
@property (nonatomic, retain) UIView* dragArea;
@end
@implementation OverlaySelectionView
@synthesize dragArea;
@synthesize delegate;
- (void) initialize {
dragAreaBounds = CGRectMake(0, 0, 0, 0);
self.userInteractionEnabled = YES;
self.multipleTouchEnabled = NO;
self.backgroundColor = [UIColor clearColor];
self.opaque = NO;
self.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
}
- (id) initWithCoder: (NSCoder*) coder {
self = [super initWithCoder: coder];
if (self != nil) {
[self initialize];
}
return self;
}
- (id) initWithFrame: (CGRect) frame {
self = [super initWithFrame: frame];
if (self != nil) {
[self initialize];
}
return self;
}
- (void)drawRect:(CGRect)rect {
// do nothing
}
#pragma mark - Touch handling
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch* touch = [[event allTouches] anyObject];
dragAreaBounds.origin = [touch locationInView:self];
}
- (void)handleTouch:(UIEvent *)event {
UITouch* touch = [[event allTouches] anyObject];
CGPoint location = [touch locationInView:self];
dragAreaBounds.size.height = location.y - dragAreaBounds.origin.y;
dragAreaBounds.size.width = location.x - dragAreaBounds.origin.x;
if (self.dragArea == nil) {
UIView* area = [[UIView alloc] initWithFrame: dragAreaBounds];
area.backgroundColor = [UIColor blueColor];
area.opaque = NO;
area.alpha = 0.3f;
area.userInteractionEnabled = NO;
self.dragArea = area;
[self addSubview: self.dragArea];
[dragArea release];
} else {
self.dragArea.frame = dragAreaBounds;
}
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
[self handleTouch: event];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
[self handleTouch: event];
if (self.delegate != nil) {
[delegate areaSelected: dragAreaBounds];
}
[self initialize];
}
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event {
[self initialize];
[self.dragArea removeFromSuperview];
self.dragArea = nil;
}
#pragma mark -
- (void) dealloc {
[dragArea release];
[super dealloc];
}
@end
然后我有一个类来实现上述定义的协议（MapViewController.h）：
#import "OverlaySelectionView.h"
typedef struct {
CLLocationDegrees minLatitude;
CLLocationDegrees maxLatitude;
CLLocationDegrees minLongitude;
CLLocationDegrees maxLongitude;
} LocationBounds;
@interface MapViewController : UIViewController<MKMapViewDelegate, OverlaySelectionViewDelegate> {
LocationBounds searchBounds;
UIBarButtonItem* areaButton;
在我的 MapViewController.m 中，areaSelected 方法是我使用 convertPoint:toCoordinateFromView: 进行触摸坐标到地理坐标转换的地方：
#pragma mark - OverlaySelectionViewDelegate
- (void) areaSelected: (CGRect)screenArea
{
self.areaButton.style = UIBarButtonItemStyleBordered;
self.areaButton.title = @"Area";
CGPoint point = screenArea.origin;
// we must account for upper nav bar height!
point.y -= 44;
CLLocationCoordinate2D upperLeft = [mapView convertPoint: point toCoordinateFromView: mapView];
point.x += screenArea.size.width;
CLLocationCoordinate2D upperRight = [mapView convertPoint: point toCoordinateFromView: mapView];
point.x -= screenArea.size.width;
point.y += screenArea.size.height;
CLLocationCoordinate2D lowerLeft = [mapView convertPoint: point toCoordinateFromView: mapView];
point.x += screenArea.size.width;
CLLocationCoordinate2D lowerRight = [mapView convertPoint: point toCoordinateFromView: mapView];
searchBounds.minLatitude = MIN(lowerLeft.latitude, lowerRight.latitude);
searchBounds.minLongitude = MIN(upperLeft.longitude, lowerLeft.longitude);
searchBounds.maxLatitude = MAX(upperLeft.latitude, upperRight.latitude);
searchBounds.maxLongitude = MAX(upperRight.longitude, lowerRight.longitude);
// TODO: comment out to keep search rectangle on screen
[[self.view.subviews lastObject] removeFromSuperview];
[self performSelectorInBackground: @selector(lookupHistoryByArea) withObject: nil];
}
// this action is triggered when user selects the Area button to start selecting area
// TODO: connect this to areaButton yourself (I did it in Interface Builder)
- (IBAction) selectArea: (id) sender
{
PoliteAlertView* message = [[PoliteAlertView alloc] initWithTitle: @"Information"
message: @"Select an area to search by dragging your finger across the map"
delegate: self
keyName: @"swipe_msg_read"
cancelButtonTitle: @"Ok"
otherButtonTitles: nil];
[message show];
[message release];
OverlaySelectionView* overlay = [[OverlaySelectionView alloc] initWithFrame: self.view.frame];
overlay.delegate = self;
[self.view addSubview: overlay];
[overlay release];
self.areaButton.style = UIBarButtonItemStyleDone;
self.areaButton.title = @"Swipe";
}
你会发现我的 MapViewController 有一个属性，areaButton。这是工具栏上的一个按钮，通常显示为 Area。当用户按下它时，他们进入了区域选择模式，此时按钮标签更改为 Swipe 来提醒他们向右滑动（可能不是最好的UI，但这就是我所拥有的）。
另请注意，当用户按下 Area 进入区域选择模式时，我会向他们显示一个警告，告诉他们需要向右滑动。由于这可能只是提醒他们需要看到的一次，因此我使用了自己的PoliteAlertView，这是一个用户可以抑制（不再显示警告）的自定义 UIAlertView。
我的 lookupHistoryByArea 只是一个方法，后台搜索我的数据库中的位置，并通过保存的 searchBounds 在地图上绘制新的覆盖物。对于你的应用程序，这显然会有所不同。
由于这是让用户选择大概区域，我认为地理精度不是关键因素。在你的应用程序中似乎也不需要考虑这一点。因此，我只绘制带有90度角的矩形，不考虑地球曲率等因素。对于几英里范围内的区域，这应该可以胜任。
我必须对你的短语 touch based drawing 进行一些假设。我认为实现应用程序最简单、触摸屏用户使用最简单的方法是用一次单独的滑动定义区域。用触摸绘制矩形需要4次滑动，引入非闭合矩形的复杂性，产生松散的形状，可能无法获得用户想要的内容。所以，我试图保持UI的简洁。如果你确实想让用户在地图上绘图，请参见这个相关的答案。
此应用程序是在ARC之前编写的，并且没有针对ARC进行更改。
在我的应用程序中，我实际上为一些在主（UI）线程和后台（搜索）线程上访问的变量使用了互斥锁，我将这些代码从此示例中删除了。根据你的数据库搜索工作方式以及你选择运行搜索的方式（GCD等），你应该确保自己线程安全性的审计。
areaSelected:是我将屏幕区域转换为地理坐标（纬度和经度）的方法。如果你有其他需求，请发布一个新问题。你上面的评论并不足以让我知道你具体遇到了什么问题。谢谢。 - NateOverlaySelectionView类是必需的。这个类是我检测用户触摸的地方，然后调用areaSelected:方法的地方。如果你真的不想向用户显示任何指示他们手指“绘制”的区域的叠加层，那没关系。你可以更改OverlaySelectionView中的代码，以便删除所有带有dragArea实例变量的代码。但是，你必须保留使用dragAreaBounds的代码，因为它将传递给areaSelected:。 - NateViewController.h
#import <UIKit/UIKit.h>
@interface ViewController : UIViewController
@end
ViewController.m
#import "ViewController.h"
#import <MapKit/MapKit.h>
@interface ViewController () <MKMapViewDelegate>
@property (weak, nonatomic) IBOutlet MKMapView *mapView;
@property (nonatomic, weak) MKPolyline *polyLine;
@property (nonatomic, strong) NSMutableArray *coordinates;
@property (weak, nonatomic) IBOutlet UIButton *drawPolygonButton;
@property (nonatomic) BOOL isDrawingPolygon;
@end
@implementation ViewController
@synthesize coordinates = _coordinates;
- (NSMutableArray*)coordinates
{
if(_coordinates == nil) _coordinates = [[NSMutableArray alloc] init];
return _coordinates;
}
- (void)viewDidLoad
{
[super viewDidLoad];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
}
- (IBAction)didTouchUpInsideDrawButton:(UIButton*)sender
{
if(self.isDrawingPolygon == NO) {
self.isDrawingPolygon = YES;
[self.drawPolygonButton setTitle:@"done" forState:UIControlStateNormal];
[self.coordinates removeAllObjects];
self.mapView.userInteractionEnabled = NO;
} else {
NSInteger numberOfPoints = [self.coordinates count];
if (numberOfPoints > 2)
{
CLLocationCoordinate2D points[numberOfPoints];
for (NSInteger i = 0; i < numberOfPoints; i++)
points[i] = [self.coordinates[i] MKCoordinateValue];
[self.mapView addOverlay:[MKPolygon polygonWithCoordinates:points count:numberOfPoints]];
}
if (self.polyLine)
[self.mapView removeOverlay:self.polyLine];
self.isDrawingPolygon = NO;
[self.drawPolygonButton setTitle:@"draw" forState:UIControlStateNormal];
self.mapView.userInteractionEnabled = YES;
}
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
if (self.isDrawingPolygon == NO)
return;
UITouch *touch = [touches anyObject];
CGPoint location = [touch locationInView:self.mapView];
CLLocationCoordinate2D coordinate = [self.mapView convertPoint:location toCoordinateFromView:self.mapView];
[self addCoordinate:coordinate];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
if (self.isDrawingPolygon == NO)
return;
UITouch *touch = [touches anyObject];
CGPoint location = [touch locationInView:self.mapView];
CLLocationCoordinate2D coordinate = [self.mapView convertPoint:location toCoordinateFromView:self.mapView];
[self addCoordinate:coordinate];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
if (self.isDrawingPolygon == NO)
return;
UITouch *touch = [touches anyObject];
CGPoint location = [touch locationInView:self.mapView];
CLLocationCoordinate2D coordinate = [self.mapView convertPoint:location toCoordinateFromView:self.mapView];
[self addCoordinate:coordinate];
[self didTouchUpInsideDrawButton:nil];
}
- (void)addCoordinate:(CLLocationCoordinate2D)coordinate
{
[self.coordinates addObject:[NSValue valueWithMKCoordinate:coordinate]];
NSInteger numberOfPoints = [self.coordinates count];
if (numberOfPoints > 2) {
MKPolyline *oldPolyLine = self.polyLine;
CLLocationCoordinate2D points[numberOfPoints];
for (NSInteger i = 0; i < numberOfPoints; i++) {
points[i] = [self.coordinates[i] MKCoordinateValue];
}
MKPolyline *newPolyLine = [MKPolyline polylineWithCoordinates:points count:numberOfPoints];
[self.mapView addOverlay:newPolyLine];
self.polyLine = newPolyLine;
if (oldPolyLine) {
[self.mapView removeOverlay:oldPolyLine];
}
}
}
#pragma mark - MKMapViewDelegate
- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay
{
MKOverlayPathView *overlayPathView;
if ([overlay isKindOfClass:[MKPolygon class]])
{
overlayPathView = [[MKPolygonView alloc] initWithPolygon:(MKPolygon*)overlay];
overlayPathView.fillColor = [[UIColor cyanColor] colorWithAlphaComponent:0.2];
overlayPathView.strokeColor = [[UIColor blueColor] colorWithAlphaComponent:0.7];
overlayPathView.lineWidth = 3;
return overlayPathView;
}
else if ([overlay isKindOfClass:[MKPolyline class]])
{
overlayPathView = [[MKPolylineView alloc] initWithPolyline:(MKPolyline *)overlay];
overlayPathView.strokeColor = [[UIColor blueColor] colorWithAlphaComponent:0.7];
overlayPathView.lineWidth = 3;
return overlayPathView;
}
return nil;
}
- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation
{
if ([annotation isKindOfClass:[MKUserLocation class]])
return nil;
static NSString * const annotationIdentifier = @"CustomAnnotation";
MKAnnotationView *annotationView = [mapView dequeueReusableAnnotationViewWithIdentifier:annotationIdentifier];
if (annotationView)
{
annotationView.annotation = annotation;
}
else
{
annotationView = [[MKAnnotationView alloc] initWithAnnotation:annotation reuseIdentifier:annotationIdentifier];
annotationView.image = [UIImage imageNamed:@"annotation.png"];
annotationView.alpha = 0.5;
}
annotationView.canShowCallout = NO;
return annotationView;
}
@end
这是我将触摸转换为 CLLocation 在 MKMapView 上的方法。
它适用于 Google 地图 和 Apple 地图：
- (void)viewDidLoad {
// ...
// ... where the _customMapView is a MKMapView object;
// find the gesture recogniser of the map
UIGestureRecognizer *_factoryDoubleTapGesture = nil;
NSArray *_gestureRecognizersArray = [_customMapView gestureRecognizers];
for (UIGestureRecognizer *_tempRecogniser in _gestureRecognizersArray) {
if ([_tempRecogniser isKindOfClass:[UITapGestureRecognizer class]]) {
if ([(UITapGestureRecognizer *)_tempRecogniser numberOfTapsRequired] == 2) {
_factoryDoubleTapGesture = _tempRecogniser;
break;
}
}
}
// my tap gesture recogniser
UITapGestureRecognizer *_locationTapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(mapLocationTouchedUpInside:)];
if (_factoryDoubleTapGesture) [_locationTapGesture requireGestureRecognizerToFail:_factoryDoubleTapGesture];
[_customMapView addGestureRecognizer:_locationTapGesture];
// ...
}
并且...
- (void)mapLocationTouchedUpInside:(UITapGestureRecognizer *)sender {
CGPoint _tapPoint = [sender locationInView:_customMapView];
CLLocationCoordinate2D _coordinates = [_customMapView convertPoint:_tapPoint toCoordinateFromView:_customMapView];
// ... do whatever you'd like with the coordinates
}