拆分NSArray到一個固定的大小和其餘

Question

我有一個NSArray在我的項目中有近12個元素。我想將這個數組分成2個數組。我想要第一個數組中的前3個元素和第二個NSArray中的其餘元素。

Answer 1

基於the answer of Alex Reynolds：

你應該具有的3的長度的範圍內，並與它的陣列的第一半，然後修改它的位置和長度，並創建所述陣列的第二個一半。

NSArray *firstThreeArray; 
NSArray *otherArray; 
NSRange threeRange; 

threeRange.location = 0; 
threeRange.length = 3; 

firstThreeArray = [wholeArray subarrayWithRange:threeRange]; 

threeRange.location = threeRange.length; 
threeRange.length = [wholeArray count] - threeRange.length; 

otherArray = [wholeArray subarrayWithRange:threeRange]; 

Answer 2

由於NSArray類別：

@implementation NSArray (NSArray_Slicing) 

- (NSArray *)subarraysFromIndex:(int)index { 
    return @[[self sliceToIndex:index], [self sliceFromIndex:index]]; 
} 


- (NSArray *)sliceFromIndex:(int)index { 
    NSMutableArray*mutArray = [self mutableCopy]; 
    NSRange range = NSMakeRange(index, self.count - index); 
    return [mutArray subarrayWithRange:range]; 
} 


- (NSArray *)sliceToIndex:(int)index { 
    NSMutableArray*mutArray = [self mutableCopy]; 
    NSRange range = NSMakeRange(0, index); 
    return [mutArray subarrayWithRange:range]; 
} 

@end 

然後調用它：

NSArray *array = @[@1, @2, @3, @4, @5, @6, @7, @8, @9, @10, @11, @12]; 
NSLog(@"First three: %@", [array sliceToIndex:3]); 
NSLog(@"Remaining: %@", [array sliceFromIndex:3]); 
NSLog(@"Sliced:  %@", [array subarraysFromIndex:3]); 
NSLog(@"Original: %@", array);