一 問題描述

查詢陣列中是否包含指定

二 問題解決

方法一

    NSArray  *array [email protected][@"abc123", @"cde234" , @"fgh456", @"ijk567", @"KLm567", @"MnO890", @"opq012", @"Rst123"];
    //匹配字串，反回結果， SELF＝＝表示陣列中每一個元素
    NSString *match1 = @"MnO890";
    NSPredicate *predicate1 = [NSPredicate predicateWithFormat:@"SELF == %@"
 
, match1];
    NSArray *results1 = [array filteredArrayUsingPredicate:predicate1];

方法二

[array enumerateObjectsWithOptions:NSEnumerationReverse usingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        if ([obj isEqualToString:@"opq012"]) {
            NSLog(@"%@-索引%d",obj, (int)idx);
        }
    }];  
 

三 拓展延伸

如何使用謂詞NSPredicate實現快速尋找。

先看下定義

NSPredicate *ca = [NSPredicate predicateWithFormat:(NSString *), ...];  

說明：
Format：有如下幾種規則

(1)比較運算子>,<,==,>=,<=,!=
可用於數值及字串
例：@"number > 100"

(2)範圍運算子：IN、BETWEEN
例：@"number BETWEEN {1,5}"
   @"address IN {'shanghai','beijing'}"

(3)字串本身:SELF 
例：@“SELF == ‘APPLE’"

(4)字串相關：BEGINSWITH、ENDSWITH、CONTAINS
例：@"
 
name CONTAIN[cd] 'ang'"    //包含某個字串
   @"name BEGINSWITH[c] 'sh'"   //以某個字串開頭
   @"name ENDSWITH[d] 'ang'"    //以某個字串結束
注:[c]不區分大小寫[d]不區分發音符號即沒有重音符號[cd]既不區分大小寫，也不區分發音符號。

(5)萬用字元：LIKE
例：@"name LIKE[cd] '*er*'"    //*代表萬用字元,Like也接受[cd].
   @"name LIKE[cd] '???er*'"

(6)正則表示式：MATCHES
例：NSString *regex = @"^A.+e$";   //以A開頭，e結尾
   @"name MATCHES %@",regex"

具體使用方法如下

1.NSString物件

    NSArray  *array [email protected][@"abc123", @"cde234" , @"fgh456", @"ijk567", @"KLm567", @"MnO890", @"opq012", @"Rst123"];
    //匹配字串，反回結果， SELF＝＝表示陣列中每一個元素
    NSString *match1 = @"MnO890";
    NSPredicate *predicate1 = [NSPredicate predicateWithFormat:@"SELF == %@", match1];
    NSArray *results1 = [array filteredArrayUsingPredicate:predicate1];

    //近似匹配字串，類似SQL中的語法
    NSString *match2 = @"fgh45";
    NSPredicate *predicate2 = [NSPredicate predicateWithFormat:@"SELF contains %@", match2];
    NSArray *results2 = [array filteredArrayUsingPredicate:predicate2];
    //不區分大小寫匹配
    NSString *match3 = @"klm567";
    NSPredicate *predicate3 = [NSPredicate predicateWithFormat:@"SELF like[cd] %@", match3];
    NSArray *results3 = [array filteredArrayUsingPredicate:predicate3];
    //正則匹配
    NSString *match4 = @"[a-zA-Z0-9]{6}";
    NSPredicate *predicate4 = [NSPredicate predicateWithFormat:@"SELF matches %@", match4];
    NSArray *results4 = [array filteredArrayUsingPredicate:predicate4];

    NSLog(@"%@\n%@\n%@\n%@\n",results1,results2,results3,results4);

輸出結果

(
    MnO890
)
(
    fgh456
)
(
    KLm567
)
(
    abc123,
    cde234,
    fgh456,
    ijk567,
    KLm567,
    MnO890,
    opq012,
    Rst123
)

2.含有屬性的物件

@interface Person: NSObject 
{
    NSString *_name;
    NSString *_telephone;
    NSInteger _id;
}

@property (nonatomic, copy) NSString *name;
@property (nonatomic, copy) NSString *telephone;
@property (nonatomic, assign) NSInteger id;

@end

1）.等於查詢

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name == %@", "張三"]; 
NSArray *filteredArray = [array filteredArrayUsingPredicate:predicate];

2）.模糊查詢

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name CONTAINS %@", @"A"]; //predicate只能是物件
NSArray *filteredArray = [array filteredArrayUsingPredicate:predicate];