通过比较特定元素来过滤 nsarray

Question

我在 Objective-C，Xcode 8.3，OSX 不是 iOS。

我有一个像这样的 NSMutableArrays

NSMutableArray* A = [NSMutableArray arrayWithObjects:@"one string", @"another string", @"third string", nil];
NSMutableArray* B = [NSMutableArray arrayWithObjects:@"one string", @"second string", nil];
NSMutableArray* C = [NSMutableArray arrayWithObjects:@"one string", @"second string", @"third string", nil];

所有数组都嵌套在另一个数组中

NSMutableArray allArrays = [NSMutableArray arrayWithObjects: A,B,C,nil];

我想过滤所有数组，这样如果最后一个元素（无论有多少项）等于 "third string"，那么除了第一个

之外，该数组的所有元素都会被删除

上面例子的结果应该是：

@[
@[@"one string"], // A
@[@"one string", @"second string"], // B
@[@"one string"]  // C
]

我已经通过迭代和比较得到了一个有效的解决方案，但必须有更有效的方法！

感谢任何帮助。

Answer 1

NSMutableArray* A = [NSMutableArray arrayWithObjects:@"one string", @"another string", @"third string", nil];
NSMutableArray* B = [NSMutableArray arrayWithObjects:@"one string", @"second string", nil];
NSMutableArray* C = [NSMutableArray arrayWithObjects:@"one string", @"second string", @"third string", nil];


NSMutableArray *allArrays = [NSMutableArray arrayWithObjects: A,B,C,nil];


for (NSMutableArray *innerArray in allArrays)
{
    //check that inner is not empty
    if (innerArray.count > 0)
    {
        //Compare the last object
        if ([[innerArray lastObject] isEqualToString:@"third string"])
        {
            //copy first string
            NSString *firstString = [innerArray firstObject];

            //remove all items from array
            [innerArray removeAllObjects];

            //Now insert copied string into empty array
            [innerArray addObject:firstString];
         }

    }

}

NSLog(@"%@",allArrays);

Answer 2

Mahesh 答案的简化版：

// enumerate the outer array
[allArrays enumerateObjectsUsingBlock:^(NSMutableArray *innerArray, NSUInteger idx, BOOL *stop){
    // test last object
    if ([innerArray.lastObject isEqualToString:@"third string"]) {
        // remove objects after the first object
        [innerArray removeObjectsInRange:NSMakeRange(1, innerArray.count - 1)];
    }
}];

通过比较特定元素来过滤 nsarray

Filter nsarray by comparing specific element

objective-c

filter

nsmutablearray