概念
Array是Swift中的结构体类型(struct), 属于是值类型.
NSArray是OC中的类型, 属于引用类型.
var aarr = ["happy", "every", "day"]
var barr : NSMutableArray = ["happy", "every", "day"]
//1
aarr[2] = "minute" //直接改变了aarr第二个元素的值
barr[2] = "minute" //让barr第二个元素指向"minute"
print("1---\(aarr)")
print("1---\(barr)")
/*输出:
1---["happy", "every", "minute"]
1---(
happy,
every,
minute
)
*/
//2
func changeA (var a:Array<String>) {
a[2] = "second" //a是对aarr的拷贝
}
func changeB (a : NSMutableArray) {
a[2] = "second" //a是对barr的引用
}
changeA(aarr) //值类型赋值时进行拷贝, 改变是a[2]的值, aarr并没有影响
changeB(barr) //引用类型赋值时传递的是引用, a[2]和barr[2]都指向同一个地址.
print("2---\(aarr)")
print("2---\(barr)")
/*输出:
2---["happy", "every", "minute"]
2---(
happy,
every,
second
)
*/
Array和NSArray之间相互转换
Swift在数组方面Array很好的兼容了OC中的NSArray,可以直接进行赋值转换.
(1) 可以直接声明Array或者NSArray, 并进行遍历
let swiftArray: Array<String> = ["10", "20","30","40","50"]
for element in swiftArray{
print(element)
}
let OCNSArray: NSArray = ["10", "20","30","40","50"]
for element in OCNSArray{
print(element)
}
(2)可以声明一个NSArray数组，转化为Array数组，再进行遍历
let OCNSArray: NSArray = ["10", "20","30","40","50"]
let swiftArray:[String] = OCNSArray as! [String]
for index in swiftArray{
print(index)
}
(3)可以声明一个Array数组，转化为NSArray，再进行遍历
let swiftArray: Array<String> = ["10", "20","30","40","50"]
let OCNSArray:NSArray = swiftArray
for index in OCNSArray{
print(index)
} 