(二) IOS学习之---NSArray& NSMuta

-NSArray

打印一个对象就是调用对象的description方法

1.创建NSArray

NSArray *array0 = @[@"abc",@"def",@"1223"]; //直接赋值元素
NSArray *array1 = [NSArray arrayWithArray:array0]; //通过arry赋值,类方法,自动释放
NSArray *array2 = [[NSArray alloc]initWithArray:array0]; //通过arry赋值,对象方法,手动释放(MRC模式下)

2.返回元素个数

NSInteger count = [array0 count];
NSLog(@"%ld",count);  // 3

3.返回指定位置元素

NSString *str0 = [array0 objectAtIndex:1];
NSLog(@"%@",str0); //def
NSString *str1 = [array0 lastObject]; //最后一个元素
NSLog(@"%@",str1); //1223
NSString *str2 = [array0 firstObject]; //第一个元素
NSLog(@"%@",str2); //abc

4.判断数组内是否包含某个对象

if([array0 containsObject:@"def"]){
    NSLog(@"包含此对象");
}

5.数组遍历方法

• 枚举器法

NSEnumerator *emumerator = [array0 objectEnumerator];
id obj;
while (obj =[emumerator nextObject]) {
   NSLog(@"%@",obj);
}

• 快速枚举法

for(id obj in array0){
  NSLog(@"%@",obj);
}

• i值遍历

for(NSInteger i = 0 ; i<array0.count;i++){
   NSLog(@"%@",[array0 objectAtIndex:i]);
}

-NSMutableArray

1.创建可变数组

NSMutableArray *mutableArray = [[NSMutableArray alloc]init];

2.添加元素

[mutableArray addObject:@"1"];  //添加一个元素
NSLog(@"%@", mutableArray);//(1)

[mutableArray addObjectsFromArray:array0];  //添加多个元素
NSLog(@"%@",mutableArray);//(1,abc,def,1223)

3.插入元素

[mutableArray insertObject:@"ghi" atIndex:3];
NSLog(@"%@",mutableArray);//(1,abc,def,ghi,1223)

4.替换元素

[mutableArray replaceObjectAtIndex:0 withObject:@"2"];
NSLog(@"%@",mutableArray);//(2,abc,def,ghi,1223)

5.删除元素

//删除指定元素
[mutableArray removeObject:@"def"];
NSLog(@"%@",mutableArray);//(2,abc,ghi,1223)
        
//删除指定下标元素
[mutableArray removeObjectAtIndex:2];
NSLog(@"%@",mutableArray);//(2,abc,1223)
        
//删除最后一个元素
[mutableArray removeLastObject];
NSLog(@"%@",mutableArray);//(2,abc)
        
//删除所有
[mutableArray removeAllObjects];
NSLog(@"%@",mutableArray);//()

6.交换元素

NSMutableArray *mArray1 = [[NSMutableArray alloc]initWithObjects:@"1",@"2",@"3", nil];
[mArray1 exchangeObjectAtIndex:0 withObjectAtIndex:1];
NSLog(@"%@",mArray1); //(2,1,3)

7.切割字符串

//按指定字符串切割
NSString *str3 = @"I am a super man + beautiful, yeah!";
NSArray *rArr1 = [str3 componentsSeparatedByString:@" "];
NSLog(@"%@",rArr1); //(I,am,a,super,man,"+","beautiful,","yeah!")

//按字符集合提供的字符切割,字符集合中的对应字符将不再出现
NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString:@"m,+"];
NSArray *rArr2 = [str3 componentsSeparatedByCharactersInSet:set];
NSLog(@"%@",rArr2); //("I a"," a super ","an "," beautiful"," yeah!")

8.拼接数组内的字符串

NSString *str4 = [mArray1 componentsJoinedByString:@"-"];
NSLog(@"%@",str4);//2-1-3

9.按照ASCII码大小排序

NSMutableArray *rArr3 = [NSMutableArray arrayWithObjects:@"r",@"D",@"a",@"R", nil];
[rArr3 sortedArrayUsingSelector:@selector(compare:)];