NSPredicate
官方定義:A definition of logical conditions for constraining a search for a fetch or for in-memory filtering.
釋義:一種邏輯條件的定義，用于約束檢索或內(nèi)存過濾的搜索。就是用于開發(fā)者自定義的條件用來檢索過濾數(shù)據(jù)集合中或?qū)ο髾z索的數(shù)據(jù)，讓你的數(shù)據(jù)過濾不再for循環(huán)。
下面直接上樣例代碼來解釋NSPredicate的用法
//先來創(chuàng)建一些數(shù)據(jù)源
Test *test1 = [[Test alloc]init];test1.name = @"absr";test1.code = @1;
Test *test2 = [[Test alloc]init];test2.name = @"asb";test2.code = @2;
Test *test3 = [[Test alloc]init];test3.name = @"raskj";test3.code = @3;
NSArray *objArray = @[test1,test2,test3];
1. 過濾生成新數(shù)據(jù) filteredArrayUsingPredicate：
//過濾出name字段長度大于某值的數(shù)據(jù)
NSPredicate *pred = [NSPredicate predicateWithFormat:@"name.length > %@",@3];
NSArray *filtArray = [objArray filteredArrayUsingPredicate:pred];
2. Array 自身過濾 filterUsingPredicate：
//過濾出name字段長度大于某值的數(shù)據(jù)，跟filteredArrayUsingPredicate區(qū)別的是filterUsingPredicate過濾后自身數(shù)據(jù)源被過濾掉了
NSMutableArray *objArray = [NSMutableArray arrayWithArray:@[test1,test2,test3]];
NSPredicate *pred = [NSPredicate predicateWithFormat:@"name.length > %@",@3];
[objArray filterUsingPredicate:pred];
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3.自身屬性做為過濾條件
//字符串?dāng)?shù)據(jù)源對象自身可以參與過濾
NSArray Testarray = @[@"oc", @"swift", @"java", @"python"];
NSPredicate pre = [NSPredicate predicateWithFormat:@"length > 4"];
NSArray *filtArray = [Testarray filteredArrayUsingPredicate:pred];
#過濾結(jié)果為 @[python];
4.對象字段屬性做為過濾條件
Test *test1 = [[Test alloc]init];test1.name = @"absr";test1.code = @1;
Test *test2 = [[Test alloc]init];test2.name = @"asb";test2.code = @2;
Test *test3 = [[Test alloc]init];test3.name = @"raskj";test3.code = @3;
NSArray *objArray = @[test1,test2,test3];
NSPredicate *pred = [NSPredicate predicateWithFormat:@"name.length > %@",@3];
NSArray *filtArray = [objArray filteredArrayUsingPredicate:pred];
#過濾結(jié)果為 @[test1,test3]；
5.字符串相關(guān)
CONTAINS(包含)
//使用CONTAINS語句過濾包含的內(nèi)容
NSArray stringArray = [[NSArray alloc]initWithObjects:@"zizhi",@"chezi",@"reiki", nil];
NSString containStr = @"zi";
NSPredicate *pre = [NSPredicate predicateWithFormat:@"SELF CONTAINS %@", containStr];
NSArray *filtArray = [stringArray filteredArrayUsingPredicate: pre])
6. SELF CONTAINS
表示自身包含 SELF前面加NOT表示相反，切記是放在SELF前不是SELF后
7.[cd]的用法
/*語法可以拼接，拼接時[cd]做為占位符，其中[c] 表示忽略大小寫，[d] 表示忽略重音符號[cd]既不區(qū)分
大小寫，也不區(qū)分發(fā)音符號。*/
NSArray testArray = [[NSArray alloc]initWithObjects:test1,test2,test3, nil];
NSString targetString = @"Ang";
NSPredicate *pred = [NSPredicate predicateWithFormat:@"title CONTAINS[cd] %@",targetString];
NSArray *filtArray = [testArray filteredArrayUsingPredicate:pred]);
8.CONTAINS 包含過濾
NSArray stringArray = [[NSArray alloc]initWithObjects:test1,test2,test3, nil];
NSString targetString = @"ang";
NSPredicate *pred = [NSPredicate predicateWithFormat:@"title CONTAINS %@",targetString];
NSArray *filtArray =[stringArray filteredArrayUsingPredicate:pred]);
BEGINSWITH(已某個字符串開頭, begins with)
NSString targetString = @"ang";
NSPredicate pred = [NSPredicate predicateWithFormat:@"title BEGINSWITH %@",targetString];
ENDSWITH(已某個字符串結(jié)尾, ends with)
NSString targetString = @"ang";
NSPredicate pred = [NSPredicate predicateWithFormat:@"title ENDSWITH %@",targetString];
9.比較運算符
== 等于
NSPredicate *pred = [NSPredicate predicateWithFormat:@"testID == %@",@12];
!= 不等于
NSPredicate *pred = [NSPredicate predicateWithFormat:@"testID != %@",@1];
> 大于
NSPredicate *pred = [NSPredicate predicateWithFormat:@"testID > %@",@12];
< 小于
NSPredicate *pred = [NSPredicate predicateWithFormat:@"testID < %@",@1];
10.范圍運算符
IN 之中
NSString
類型，判斷title屬性是否是字符串@"angle"和@"addss"中的一個：NSPredicate *pred = [NSPredicate predicateWithFormat:@"title IN {'angle', 'addss'}"];
IN 之中
NSNumber
類型，判斷testID屬性是否是NSNumber對象中的@1和@13中的一個：NSPredicate *pred = [NSPredicate predicateWithFormat:@"testID IN {1, 13}"]
11.BETWEEN 之間
{1, 13}包括1和13：
NSPredicate *pred = [NSPredicate predicateWithFormat:@"testID BETWEEN {1, 13}"]
12.通配符 LIKE(也可以接[cd])
//包含過濾
NSPredicate pred = [NSPredicate predicateWithFormat:@"title LIKE 'da*'"];
字符串包含ang即 如“danche”、“zidan”
13.? 通配一個字符
//單字符匹配過濾，如“ing”通配 ;“jing”因為是“ji”兩個字符就不通配
NSPredicate pred = [NSPredicate predicateWithFormat:@"title LIKE '?ng'"];
14.AND(或&&)
//AND多條件集合，累死sql語句中的and
NSPredicate *pred = [NSPredicate predicateWithFormat:@"testID >= %@ AND testID <=%@", @11, @13];
15.OR(或||)
//OR或語法過濾
NSPredicate *pred = [NSPredicate predicateWithFormat:@"title == 'angle' OR title == 'lenang'"];
16.NOT(或!)
從一個數(shù)組中過濾掉另外一個數(shù)組的所有數(shù)據(jù)
//NOT非語法過濾
NSArray arrayFilter = @[@"abc1", @"abc2"];
NSArray arrayContent = @[@"a1", @"abc1", @"abc4", @"abc2"];
NSPredicate *thePredicate = [NSPredicate predicateWithFormat:@"NOT (SELF in %@)", arrayFilter];
NSLog(@"%@",[arrayContent filteredArrayUsingPredicate:thePredicate]);
17. 為對象指定字段過濾
NSPredicate *pred = [NSPredicate predicateWithFormat:@" NOT (testID IN %@ )",@[@1, @2]];
18.匹配檢測
//對象匹配檢測
-(BOOL)evaluateWithObject:(id)object;
Block
Test *test1 = [[Test alloc]init];
test1.name = @"absr";
test1.code = @1;
NSPredicate *pres = [NSPredicate predicateWithFormat:@"code == %@", @2];
BOOL match = [pres evaluateWithObject:test1];
19.block匹配
-(NSPredicate)predicateWithBlock:(BOOL (^)(id evaluatedObject, NSDictionary bindings))block
NSArray array = @[@"jim", @"cook", @"jbos"];
NSPredicate pre = [NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary bindings) {
return [[evaluatedObject valueForKey:@"name"] isEqualToString:@"cook"];
}];
NSArray aray = [array filteredArrayUsingPredicate:pre];
block中第二個參數(shù)NSDictionary bindings我看好多文章都寫不知道是干嘛的，這里就簡單講一下代表其實就是需要篩選的數(shù)組對象的其中一個成員，第二個參數(shù)是傳過來的參數(shù)，如下代碼中的@{@"$VALUES":@"name"},可以打個斷點觀察一下。
NSPredicate* predicateBlock = [NSPredicate predicateWithBlock:^BOOL(id _Nonnull evaluatedObject, NSDictionary<NSString *,id> * _Nullable bindings) {
NSLog(@"%@",bindings);
return YES;
}];
[predicateBlock evaluateWithObject:nil substitutionVariables:@{@"$VALUES":@"name"}];
20.組合過濾
//一個或一組NSPredicate形成新的過濾條件
Test *test1 = [[Test alloc]init];test1.name = @"absr";test1.code = @1;
Test *test2 = [[Test alloc]init];test2.name = @"asb";test2.code = @2;
Test *test3 = [[Test alloc]init];test3.name = @"raskj";test3.code = @3;
NSArray *array = @[test1,test2,test3];
NSPredicate *pre1 = [NSPredicate predicateWithFormat:@"code >= %@",@1];
NSPredicate *pre2 = [NSPredicate predicateWithFormat:@"code <= %@",@2];
//以AND形式組合
NSPredicate *andPre = [NSCompoundPredicate andPredicateWithSubpredicates:@[pre1,pre2]];
//以O(shè)R形式組合
NSPredicate *orPre = [NSCompoundPredicate orPredicateWithSubpredicates:@[pre1, pre2]];
//過濾條件以外的數(shù)據(jù)
NSPredicate *notPre = [NSCompoundPredicate notPredicateWithSubpredicate:pre2];
NSArray *filtArray = [array filteredArrayUsingPredicate:orPre];
關(guān)于 NSPredicate的用法還有好多好多，大家可以自己慢慢實踐
