单例模式

单例模式：传值
单一的实例 唯一的对象 全工程中唯一的一个对象
作用是通过单例来保存工程中的多个页面中共享的对象和数据
生命周期和程序的生命周期一样 当程序结束时单例对象释放掉

/*单例类.h**/
继承自NSObject：因为只处理数据，不需要显示，不需要控制传值

#import<Foundation/Foundation.h>

@interface DataHandle : NSObject

+(instancetype)shareDateHandle;
@property(nonatomic,copy)NSString dataTitle;
@property(nonatomic,retain)NSMutableArray allKeysArray;

@end
/**/

/*单例类.m**/

#import “DataHandle.h”

@implementation DataHandle
+(instancetype)shareDateHandle
{

//static声明静态变量
//特点：静态变量存储在静态区（全局区）只能初始化一次

static  DataHandle  *dataHandle = nil;
if (dataHandle == nil) {
    dataHandle = [[DataHandle alloc]init];
    [dataHandle setStudentDic];
}


return dataHandle;

}
@end
/*/

/***取出数据**/
-(void)setStudentDic
{
NSString filePath = [[NSBundle mainBundle] pathForResource:@”Students” ofType:@”plist”];
//通过文件路径取出字典
NSMutableDictionary bigDic = [NSMutableDictionary dictionaryWithContentsOfFile:filePath];
NSLog(@”bigDic = %@”,bigDic);

self.allStuDic = [NSMutableDictionary dictionary];

for (NSString *key in bigDic) {

    NSMutableArray *array = [bigDic objectForKey:key];

    NSMutableArray *stuArray = [NSMutableArray array];

    for (NSMutableDictionary *dic in array) {

        Student *stu = [[Student alloc] init];

// stu.name = [dic objectForKey:@”name”];
//使用KVC间接给属性赋值
[stu setValuesForKeysWithDictionary:dic];
[stuArray addObject:stu];
[stu release];

    }

    [self.allStuDic setObject:stuArray forKey:key];

}


 self.allKeysArray = [NSMutableArray       arrayWithArray:self.allStuDic.allKeys];

//数组排序
[self.allKeysArray sortUsingSelector:@selector(compare:)];

}
/**/

`