[英]how can I append element into two-dimensional array in swift?
I'm having a big trouble using 2D array in swift. 我在快速使用2D数组时遇到了很大的麻烦。 in Objective-c, I could use 2d array like below.
在Objective-c中,我可以使用如下所示的2d数组。
NSMutableArray *arrMain = [[NSMutableArray alloc] init];
NSMutableArray *arrSub = [[NSMutableArray alloc] init];
[arrMain addObject:arrSub];
[arrSub addObjects:@[@"1",@"2",@"3",@"4"]]
NSLog(@"arrayMain:%@",arrMain);
and it displayed all objects in arrSub. 并在arrSub中显示所有对象。 However, in swift it display nothing.
但是,它很快不显示任何内容。 I guess it is because of reference type.
我猜是因为引用类型。 How can I append(or refer) second array like objective-c?
我如何附加(或引用)第二个数组,如Objective-C?
var arr1 = [1,2,3]
var arr2 = [arr1]
print(arr2) // [[1, 2, 3]]
arr1.append(0)
print(arr1) // [1, 2, 3, 0]
arr2.append([5,6])
print(arr2) // [[1, 2, 3], [5, 6]]
withUnsafeMutablePointer(&arr2) { (parr2) -> Void in
parr2.memory[0].append(4)
}
print(arr2) // [[1, 2, 3, 4], [5, 6]]
be careful! 小心! it is really unsafe ... you have to know exactly, what are you doing
这真的很不安全...您必须确切地知道,您在做什么
In Objective-C,NSArray、NSMutableArray both reference type.In Swift,Array is value type. 在Objective-C中,NSArray,NSMutableArray都是引用类型。在Swift中,Array是值类型。 You can creat 2D array like this:
您可以像这样创建2D数组:
var array1 = [[Int]]() // modus 1
array1.append([10])
var array2 = Array<Array<Int>>() // modus 2
I think modus 1 is clear 我认为方式1很清楚
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