Adding an object at a specific index of an NSMutableArray

问题

How can an object be added at a specific index of an NSMutableArray?

How is an object added to the front of the array?

回答1:

[myMutableArray insertObject:myObject atIndex:42];

To add an object to the front of the array, use 0 as the index:

[myMutableArray insertObject:myObject atIndex:0];

回答2:

Take a look at the insertObject:atIndex: method of the NSMutableArray class. Adding to the "front" of the array implies index 0.

For example:

NSMutableArray * array = [[NSMutableArray alloc] initWithCapacity:3];
[array addObject:@"b"]; // Contains "b"
[array insertObject:@"a" atIndex:0]; // Contains "a", "b"
[array insertObject:@"c" atIndex:2]; // Contains "a", "b", "c"

回答3:

Updated for Swift 3:

If you want to Add an object at a specific index of a NSMutableArray, use below a simple line of code:

self.yourMutableArrayName.insert(<#T##newElement: String##String#>, at: <#T##Int#>)

Example: if you want to add string: "Nature" at index: 3

var str = "Nature"
self.yourMutableArrayName.insert(str, at: 3) 

// Enjoy..! 

来源：https://stackoverflow.com/questions/5137359/adding-an-object-at-a-specific-index-of-an-nsmutablearray