依据当前位置，计算方圆1000内的所有其他学校坐标代码,ObjC代码库,德仔网

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【ObjC】依据当前位置，计算方圆1000内的所有其他学校坐标

作者:Dezai.CN / 发布于2013/7/25/ 1040

所有学校的地图经纬度坐标都保存数据库中，依据传入的经纬度，计算出方圆1000米访问的最大和最小经纬度数值，然后调用SQL语句，就可以查找出该范围内所有学校


	-(void)initSchoolByjinduweidu:(NSString*)s_lg withParam:(NSString *)s_lt whitePara2:(double)dis{
	
	dis=1.0;
	//------------
	float d_lng=2*asin(sin(dis/(2*EARTH_RADIUS))/cos(([s_lt floatValue])));
	d_lng= RADIANS_TO_DEGREES(d_lng);
	
	float d_lat = dis/EARTH_RADIUS;
	d_lat= RADIANS_TO_DEGREES(d_lat);
	
	float d_lng_max=([s_lg floatValue]+fabs(d_lng));
	float d_lng_min=([s_lg floatValue]-fabs(d_lng));
	
	float d_lat_max=([s_lt floatValue]+fabs(d_lat));
	float d_lat_min=([s_lt floatValue]-fabs(d_lat));
	
	//--------
	
	// NSLog(@"s_lg:%@ d_lng:%f d_lng_max:%f d_lng_min:%f",s_lg,d_lng,d_lng_max,d_lng_min);
	//NSLog(@"s_lt:%@ d_lat:%f d_lat_max:%f d_lat_min:%f",s_lt,d_lat,d_lat_max,d_lat_min);
	
	
	self.schoollist_id=[NSMutableArray array];
	self.schoollist_name=[NSMutableArray array];
	self.schoollist_type=[NSMutableArray array];
	self.schoollist_addr=[NSMutableArray array];
	self.schoollist_lg=[NSMutableArray array];
	self.schoollist_lt=[NSMutableArray array];
	self.schoollist_property=[NSMutableArray array];
	self.schoollist_stage=[NSMutableArray array];
	
	self.schoollist_commentnum=[NSMutableArray array];
	self.schoollist_content=[NSMutableArray array];
	
	self.schoollist_likenum=[NSMutableArray array];
	
	self.schoollist_piclist=[NSMutableArray array];
	
	
	
	self.schoollist_publishtime=[NSMutableArray array];
	
	
	
	self.schoollist_summary=[NSMutableArray array];
	
	
	
	
	
	if (SQLITE_OK != sqlite3_open([self getFilePath ], &pdb;)){
	return;
	}
	
	char* sql ="";
	
	
	sql = "select * from schoollist where s_lg>? and s_lg<? and s_lt>? and s_lt<?;";//查询语句
	
	
	sqlite3_stmt* stmt;
	
	if (sqlite3_prepare_v2(pdb, sql, -1, &stmt;, nil)==SQLITE_OK) {//准备
	
	sqlite3_bind_text(stmt, 1,[[NSString stringWithFormat:@"%f",d_lng_min]UTF8String], -1, NULL);
	
	sqlite3_bind_text(stmt, 2,[[NSString stringWithFormat:@"%f",d_lng_max]UTF8String], -1, NULL);
	
	sqlite3_bind_text(stmt, 3,[[NSString stringWithFormat:@"%f",d_lat_min]UTF8String], -1, NULL);
	
	sqlite3_bind_text(stmt, 4,[[NSString stringWithFormat:@"%f",d_lat_max]UTF8String], -1, NULL);
	
	}else{
	return;
	}
	
	
	
	while( SQLITE_ROW == sqlite3_step(stmt) ){//执行
	
	char* _s_addr = (char*)sqlite3_column_text(stmt, 1);
	
	
	
	}//while
	
	
	
	sqlite3_finalize(stmt);
	sqlite3_close(pdb);
	
	
	
	}

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