Question

我正在使用NSMutableArray。我希望像在SQL group by "log_date"中一样按日期获取值。

logMuArray (
        {
        "log_currenttime" = "4:30pm";
        "log_date" = "11.12.2011";
        "log_duration" = "1:30";
    },
        {
        "log_currenttime" = "4:33pm";
        "log_date" = "11.12.2011";
        "log_duration" = "2:21";
    },
        {
        "log_currenttime" = "4:40pm";
        "log_date" = "11.12.2011";
        "log_duration" = "5:30";
    },
        {
        "log_currenttime" = "7:30pm";
        "log_date" = "12.12.2011";
        "log_duration" = "1:30";
    },
        {
        "log_currenttime" = "7:33pm";
        "log_date" = "12.12.2011";
        "log_duration" = "2:21";
    },
        {
        "log_currenttime" = "7:40pm";
        "log_date" = "12.12.2011";
        "log_duration" = "5:30";
    },
        {
        "log_currenttime" = "07:16pm";
        "log_date" = "19.12.2011";
        "log_duration" = "0:07";
    },
        {
        "log_currenttime" = "7:31pm";
        "log_date" = "19.12.2011";
        "log_duration" = "0:04";
    },
        {
        "log_currenttime" = "7:33pm";
        "log_date" = "19.12.2011";
        "log_duration" = "0:03";
    },
        {
        "log_currenttime" = "7:33pm";
        "log_date" = "19.12.2011";
        "log_duration" = "0:06";
    },
        {
        "log_currenttime" = "7:35pm";
        "log_date" = "19.12.2011";
        "log_duration" = "0:05";
    }
)

**所以，我刚刚表演了......

 NSLog(@"logMuArray %@",[logMuArray valueForKey:@"log_date"]);

但我只想获取UNIQUE日期。** 我考虑过NSPredicate或Mutable Set等......

logMuArray (
    "11.12.2011",
    "11.12.2011",
    "11.12.2011",
    "12.12.2011",
    "12.12.2011",
    "12.12.2011",
    "19.12.2011",
    "19.12.2011",
    "19.12.2011",
    "19.12.2011",
    "19.12.2011"
)

提前致谢.....

修改

我也听说过“@distinctUnionOfObjects”

...

Answer 1

Shanti的答案很接近。您想要使用键值编码集合运算符@distinctUnionOfObjects。将操作员放在您想要影响的密钥之前，就像它是您正在访问的密钥路径的一部分一样：

[logMuArray valueForKeyPath:@"@distinctUnionOfObjects.log_date"]

注意valueForKeyPath:的使用，而不是valueForKey:前者是键值编码协议中的一种方法，允许访问任意深度的属性。关键路径是由点分隔键组成的NSString。每个键查找的结果依次用于访问下一个键（从原始接收器开始）;默认情况下，只需在每一步调用valueForKey:。

Answer 2

您可以使用KVC。

[logMuArray valueForKey:@"@distinctUnionOfArrays.log_date"]

编辑：编辑此作为乔希的回应

[logMuArray valueForKeyPath:@"@distinctUnionOfArrays.log_date"]

Answer 3

您应该将NSSet用于UNIQUE项目，例如：

NSSet *filteredData = [NSSet setWithArray:[logMuArray valueForKey:@"log_date"]];

Answer 4

试试这个逻辑可能对你有帮助

-(NSMutableArray *) makeUnique :(NSMutableArray *) array {    
    int i;
    int count = [array count];
    for (i =0; i< count ; i++) {
        NSRange range = NSMakeRange (i+1, count); 
        [array removeObject:[array objectAtIndex:i] inRange:range];
    }
    return array;
}

Answer 5

您可以合并一套

以下是一些示例代码

NSMutableArray * mArray = [NSMutableArray array];
NSDictionary *d1 = [NSDictionary dictionaryWithObjectsAndKeys:@"foo",@"bar",@"bar",@"oooo",nil];
NSDictionary *d2 = [NSDictionary dictionaryWithObjectsAndKeys:@"boo",@"bar",@"bar",@"oooo",nil];
NSDictionary *d3 = [NSDictionary dictionaryWithObjectsAndKeys:@"boo",@"bar",@"bar",@"oooo",nil];
[mArray addObject:d1];
[mArray addObject:d2];
[mArray addObject:d3];
NSLog(@"the array\n%@", mArray);
NSLog(@"just bar %@", [mArray valueForKey:@"bar"]);
//get unique values
NSSet * set = [NSSet setWithArray:[mArray valueForKey:@"bar"]];
NSLog(@"unique just bar %@", [set allObjects]);

这是输出

2011-12-20 01:50:59.034 TestEnvironment[32401:207] the array
(
        {
        bar = foo;
        oooo = bar;
    },
        {
        bar = boo;
        oooo = bar;
    },
        {
        bar = boo;
        oooo = bar;
    }
)
2011-12-20 01:50:59.036 TestEnvironment[32401:207] just bar (
    foo,
    boo,
    boo
)
2011-12-20 01:50:59.038 TestEnvironment[32401:207] unique just bar (
    foo,
    boo
)

如何在NSMutableArray中实现“按值分组”？

5 个答案: