Flatten an NSArray | 易学教程

问题

I have an array like this:

array: (
    (
        "http://aaa/product/8_1371121323.png",
        "http://aaa/product/14_1371123271.png"
    ),
    (
        "http://aaa/product/9_1371121377.png"
    )
)

and I have to create another array from that one like this

array: (
    "http://aaa/product/8_1371121323.png",
    "http://aaa/product/14_1371123271.png",
    "http://aaa/product/9_1371121377.png"
)

How can I do that? Is it possible to combine all the objects and separate them using some string?

回答1:

Sample Code :

NSMutableArray *mainArray = [[NSMutableArray alloc] init];
for (int i = 0; i < bigArray.count ; i++)
{
     [mainArray addObjectsFromArray:[bigArray objectAtIndex:i]];
}
NSLog(@"mainArray :: %@",mainArray);

回答2:

It can be done in a single line if you like key-value coding (KVC). The @unionOfArrays collection operator does exactly what you are looking for.

You may have encountered KVC before in predicates, bindings and similar places, but it can also be called in normal Objective-C code like this:

NSArray *flatArray = [array valueForKeyPath: @"@unionOfArrays.self"];

There are other collection operators in KVC, all prefixed with an @ sign, as discussed here.

回答3:

Sample code:

NSArray* arrays = @(@(@"http://aaa/product/8_1371121323.png",@"http://aaa/product/14_1371123271.png"),@(@"http://aaa/product/9_1371121377.png"));
NSMutableArray* flatArray = [NSMutableArray array];
for (NSArray* innerArray in arrays) {
    [flatArray addObjectsFromArray:innerArray];
}

NSLog(@"%@",[flatArray componentsJoinedByString:@","]);

回答4:

NSMutableArray *arr1 = [NSMutableArray arrayWithArray:[initialArray objectAtIndex:0]];
[arr1 addObjectsFromArray:[initialArray objectAtIndex:1]];

Now arr1 contains all the objects

来源：https://stackoverflow.com/questions/17087380/flatten-an-nsarray

标签

objective-c

cocoa

nsarray