1. 數組的常用處理方式 // 不可變數組 //1.數組的創建 NSString *s1 = @"zhangsan"; NSString *s2 = @"lisi"; NSString *s3 = @"wangwu"; //(1) NSArray *array1 = [[NSArray alloc] ...
1. 數組的常用處理方式
//--------------------不可變數組
//1.數組的創建
NSString *s1 = @"zhangsan";
NSString *s2 = @"lisi";
NSString *s3 = @"wangwu";
//(1)
NSArray *array1 = [[NSArray alloc] initWithObjects:s1,s2,s3, nil];
NSLog(@"%@",array1); //等價於 array1.descripton
//(2)使用類方法創建
NSArray *array2 = [NSArray arrayWithObjects:s1,s2,s3, nil];
//(3)創建一個數組對象，同時往裡面存入一元素
NSArray *array3 = [NSArray arrayWithObject:s1];
//(4)創建一個數組，此數組中的元素來自array1
NSArray *array4 = [NSArray arrayWithArray:array1];
NSLog(@"array4 = %@",array4);
//2.通過下標取元素
NSString *str1 = [array4 objectAtIndex:0];
//3.數組元素的個數
NSUInteger count = [array4 count]; //等價於：array4.count;
//4.判斷數組中的是否包含某個元素
BOOL isContains = [array4 containsObject:@"zhangsan"];
NSLog(@"isContains:%d",isContains);
//5.查找某一個對象在數組中的下標位置
NSUInteger index = [array4 indexOfObject:@"wangwu"];
if (index == NSNotFound) {
NSLog(@"Not find elemnts");
} else {
NSLog(@"index = %ld",index);
}
//6.鏈接數組中的字元串(前提：數組中都是字元串）
NSString *joinString = [array4 componentsJoinedByString:@","];
NSLog(@"joinString = %@",joinString);
//7.訪問數組最後一個元素
NSString *lastObj = [array4 lastObject]; //array4.lastObject
NSLog(@"lsatObj = %@",lastObj);
//8.再原路的數組後面添加一個元素
NSArray *array5 = [array4 arrayByAddingObject:@"zhaolia"];
NSLog(@"array5 = %@",array5);
//取對應下標元素
int idx=4;
if (idx <array5.count) {
NSString *s = [array5 objectAtIndex:idx];
NSLog(@"s = %@",s);
}
//--------------數組的遍歷
//1.普通遍歷
for (int i=0; i<array5.count; i++) {
NSString *str = [array5 objectAtIndex:i];
NSLog(@"%@",str);
}
//快速遍歷
for (NSString *s in array5) {
NSLog(@"%@",s);
}
//4.4之後的優化
//1.創建一個素組
NSArray *array7 = @[s1,s2,s3]; //等價於：NSArray *array7 = [NSArray arrayWithObjects:s1,s2,s3,nil];
NSLog(@"array7 = %@",array7);
NSString *str = array7[0];
NSLog(@"array[7] = %@",str);
//------------------可變數組
//初始化，設定元素個數為5，可以更改的。（繼承自NSArray）
NSMutableArray *mutableArray = [NSMutableArray arrayWithCapacity:5];
//想數組中添加一個元素
[mutableArray addObject:@"aaa"];
//向數組中指定下標插入元素
[mutableArray insertObject:@"ccc" atIndex:0];
NSLog(@"%@",mutableArray); //原來位置元素後移
//移除最後一個元素
[mutableArray removeLastObject];
NSLog(@"移除最後元素後：%@",mutableArray);
//移除指定元素
[mutableArray removeObject:@"aaa"];
//移除指定下標元素
[mutableArray removeObjectAtIndex:0];
//向數組中添加數組
[mutableArray addObjectsFromArray:array1];
//1.創建可變數組
NSString *t1 = @"zhangsan ";
NSString *t2 = @"lisi";
NSString *t3 = @"wangwu ";
// NSMutableArray *mArray1 = @[s1,s2,s3];//wrong.這裡創建了一個不可變數組
NSMutableArray *mArray1 = [[NSMutableArray alloc] initWithObjects:s1,s2,s3, nil];
//創建數組時，開闢3個空間用於存儲元素，存儲超過容量，數組自動增大空間
NSMutableArray *mArray2 = [[NSMutableArray alloc] initWithCapacity:3];
NSMutableArray *mArray3 = [NSMutableArray arrayWithCapacity:3];
//2.添加元素
[mArray2 addObject:t1];
[mArray2 addObject:t2];
[mArray2 addObject:t3];
NSLog(@"mArray2= %@",mArray2);
//將mArray2 中元素添加到mArray3中
// [mArray3 addObjectsFromArray:mArray2];
//將mArray2作為二維數字添加
[mArray3 addObject:mArray2];
NSLog(@"mArray3 = %@",mArray3);
//3.插入元素
[mArray2 insertObject:@"Jack" atIndex:0];
NSLog(@"mArray2 = %@",mArray2);
//4.替換元素
[mArray2 replaceObjectAtIndex:0 withObject:@"John"];
NSLog(@"替換：%@",mArray2);
//5.互換兩個元素的位置
[mArray2 exchangeObjectAtIndex:3 withObjectAtIndex:0];
NSLog(@"mArray2 = %@",mArray2);
//6.刪除元素
//6.1根據下標刪除
[mArray2 removeObjectAtIndex:2];
NSLog(@"mArray2 = %@",mArray2);
//6.2刪除最後一個元素
[mArray2 removeLastObject];
NSLog(@"mArray2 = %@",mArray2);
//6.3刪除指定的對象
//[mArray2 removeObject:@"zhangsan"];
//6.4刪除所有元素
[mArray2 removeAllObjects];
NSLog(@"mArray2 = %@",mArray2);
