objective-c - 如何在 ObjC 中对数组进行排序

Question

我正在寻找一个数组（mainArray），包含几个数组（array1,2,3,...）
比较器（NSnumber）位于每个array1,2,3中的index8 ...

我应该使用哪种方法？

你有什么解决办法吗？
非常感谢

干杯

蒂姆

Answer 1

您可以对NSMutableArray.

// Create an array of arrays of integers using the new array and number literal syntax 
NSMutableArray* arrayOfArrays = 
    [NSMutableArray arrayWithArray:@[ @[ @0, @1, @2 ], @[ @1, @2, @3 ] ];

// The key on which to sort is located at this index in each array
NSUInteger sortKeyIndex = 2;

// Sort the array of arrays using a stable sort. This means that arrays which considered
// equal in arrayOfArrays will retain their relative positions in the sorted arrayOfArrays
// Use a comparator block to sort arrayOfArrays. 
[arrayOfArrays sortWithOptions:NSSortStable 
               usingComparator:^(id lhs, id rhs) {
    // Cast the two elements of arrayOfArrays being compared to their actual type (NSArray)
    NSArray* lhsArray = lhs;
    NSArray* rhsArray = rhs;

    // Extract the element of each array which is used as a sort key
    // This makes use of the new array index syntax
    NSNumber* lhsNumber = lhsArray[sortKeyIndex];
    NSNumber* rhsNumber = rhs[sortKeyIndex];

    // Unbox the integers from each NSNumber to get the actual values of the sort keys
    NSInteger lhsSortKey = [lhs integerValue];
    NSInteger rhsSortKey = [rhs integerValue];

    // Compare the two sort keys
    if (lhsSortKey < rhsSortKey) {
        return NSOrderedAscending;
    } else if (lhsSortKey > rhsSortKey) {
        return NSOrderedDescending;
    } else {
        return NSOrderedSame;
    }
}];

Answer 2

如果使用比较器对 NSArray 进行排序，则可以完全控制每个比较。
所以你可以使用：

array=[array sortedArrayUsingComparator: ^ NSComparisonResult (id obj1, id obj2)
{
    // obj1 and obj2 are two arrays
    NSNumber* n1=[obj1 objectAtIndex:8];
    NSNumber* n2=[obj2 objectAtIndex: 8];
    <compare the numbers and return NSOrderedAscending, NSOrderedSame or NSOrderedDescending>
}];