iOS开发：NSSet的使用

NSSet在初始化的时候，赋值的时候如果放入两个相同元素的话，会自动删除其中一个相同的元素。eg：
NSSet *set1 = [[NSSet alloc] initWithObjects:@“a”,@“b”,@“c”,@“d”, nil]; //初始化集合
[set1 count]; //返回集合中的个数

NSMutableSet *mSet1 = [[NSMutableSet alloc] initWithObjects:@"1",@"2",@"3", nil];
NSMutableSet *mSet2 = [[NSMutableSet alloc] initWithObjects:@“1”,@“4”,@“5”, nil];
[mSet1 unionSet:mSet2];        //取出并集1，2，3，4，5
[mSet1 intersectSet:mSet2];  //取交集1
[mSet1 minusSet:mSet2];       //删除mSet1中与mSet2相同的元素 结果为:2，3，4，5

BOOL ret1 = [set1 containsObject:@“Apple”];  //判断集合中是否含有@“Apple”

NSSet *set2 = [[NSSet alloc] initWithObjects:@“a”,@“b”,@“c”,@“d”, nil];
BOOL ret1 = [set isEqualToSet:set2]; //判断两个集合是否相等   
5、判断set2是否是set3的子集
NSSet *set3 = [[NSSet alloc] initWithObjects:@“a”,@“b”,@“c”,@“d”,@“e”, nil];
BOOL  ret2 = [set2 isSubsetOfSet:set3];  //判断set2是否是set3的子集合

NSEnumerator  *enumerator = [set objectEnumerator];
NSString  *str;
while (str = [enumerator nextObject]) {
  ……
}

NSArray  *array1 = [[NSArray alloc] initWithObjects:@“1”,@“2”,@“3”,@“4”, nil];
NSSet  *set = [[NSSet alloc] initWithArray:array1];

NSArray  *array2 = [set allObjects];

NSMutableSet *mSet1 = [NSMutableSet setWithObjects:@"1", @“2”, @“3”, @“4”, nil];  //可变集合初始化
NSMutableSet *mSet2 = [NSMutableSet setWithCapacity:0]; //可变集合

[mSet1 addObject:@“5”];
[mSet1 addObject:@“6”];
[mSet1 addObject:@“6”];  //如果添加的元素有重复，实际情况只保留一个相同的元素

[mSet1 removeObject:@“3”];
[mSet1 removeAllObjects];

NSIndexSetNSIndexSet  *indexSet1 = [[NSIndexSet alloc] initWithIndexesInRange:NSMakeRange(1,3)]; //集合中的数字是1 2 3
//根据集合提取数组中指定位置的元素
NSArray  *array1 = [[NSArray alloc] initWithObjects:@“1”,@“2”,@“3”,@“4”, nil];
NSArray  *array2 = [array1 objectsAtIndexes:indexSet]; //返回2 3 4

NSMutableIndexSet *indexSet2 =[[NSMutableIndexSet alloc] init];
[indexSet2 addIndex:0];
[indexSet2 addIndex:2];
[indexSet2 addIndex:4]; //通过集合获取数组中指定元素
NSArray *array3 = [[NSArray alloc] initWithObjects:@“1”,@“2”,@“3”,@“4”,@“5”,@“6”, nil];
NSArray *array4 = [array3 objectsAtIndexes:indexSet];  //返回1 3 5

#import <Foundation/Foundation.h>
@interface JSHistoryTool : NSObject
(instancetype)sharedHistoryTool;
// 存储 **操作历史记录
(void)writeTemp:(NSString *)temp time:(NSString *)time;
// 取出 **操作历史记录
(NSArray *)getValue;
@end

#import "JSHistoryTool.h"
@implementation JSHistoryTool
(instancetype)sharedHistoryTool {
 static id instance = nil;
 static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        instance = [[self alloc]init];
    });
 return instance;
}
(void)writeTemp:(NSString *)temp time:(NSString *)time {
    NSArray *arr = [[NSUserDefaults standardUserDefaults] valueForKey:@"set"];
    NSMutableSet *sSet = [[NSMutableSet alloc] initWithArray:arr]; //先把现有存储的数组取出来，然后根据数组元素进行去重，最后再进行存储
    [sSet addObject:@{@"Temp":temp, @"Time":time}];
    NSArray *aa = [sSet allObjects];
    NSMutableArray *marr = [[NSMutableArray alloc] initWithArray:aa];
 if (marr.count > 20) {
        [marr removeObjectAtIndex:0];
    }
    [[NSUserDefaults standardUserDefaults] setObject:marr forKey:@"set"];
}
(NSArray *)getValue {
    NSArray *arr = [[NSUserDefaults standardUserDefaults] valueForKey:@"set"];
 return [[arr reverseObjectEnumerator] allObjects];
}
@end

(void)sendClick {
 if (![JSBLECenterManager sharedInstance].characteristic) {
 return;
    }
    _tempValue = [NSString stringWithFormat:@"%.0f", _centigradeDegree];
    _timeValue = [NSString stringWithFormat:@"%.0ld", (long)_timeDegree];
    _waterValue = [NSString stringWithFormat:@"%.0f", _waterDegree];
    NSString *ttData = [NSString stringWithFormat:@"TEA%@,%@,%@U", _tempValue, _timeValue, _waterValue];
    NSMutableSet *set1 = [[NSMutableSet alloc] initWithObjects:_tempValue, _timeValue, nil]; //初始化可变集合
    [[JSHistoryTool sharedHistoryTool] writeTemp:_tempValue time:_timeValue]; //通过工具类进行存储操作
    NSData *data = [ttData dataUsingEncoding:NSUTF8StringEncoding];
 // 根据上面的特征self.characteristic来写入数据
    [[JSBLECenterManager sharedInstance].peripheral writeValue:data forCharacteristic:[JSBLECenterManager sharedInstance].characteristic type:CBCharacteristicWriteWithResponse];
}