iOS中NSArray数组常用处理方式
1. 数组的常用处理方式
//--------------------不可变数组 //1.数组的创建 NSString *s1 = @"zhangsan"; NSString *s2 = @"lisi"; NSString *s3 = @"wangwu"; //(1) NSArray *array1 = [[NSArray alloc] initWithObjects:s1,s2,s3, nil]; NSLog(@"%@",array1); //等价于 array1.descripton //(2)使用类方法创建 NSArray *array2 = [NSArray arrayWithObjects:s1,s2,s3, nil]; //(3)创建一个数组对象,同时往里面存入一元素 NSArray *array3 = [NSArray arrayWithObject:s1]; //(4)创建一个数组,此数组中的元素来自array1 NSArray *array4 = [NSArray arrayWithArray:array1]; NSLog(@"array4 = %@",array4); //2.通过下标取元素 NSString *str1 = [array4 objectAtIndex:0]; //3.数组元素的个数 NSUInteger count = [array4 count]; //等价于:array4.count; //4.判断数组中的是否包含某个元素 BOOL isContains = [array4 containsObject:@"zhangsan"]; NSLog(@"isContains:%d",isContains); //5.查找某一个对象在数组中的下标位置 NSUInteger index = [array4 indexOfObject:@"wangwu"]; if (index == NSNotFound) { NSLog(@"Not find elemnts"); } else { NSLog(@"index = %ld",index); } //6.链接数组中的字符串(前提:数组中都是字符串) NSString *joinString = [array4 componentsJoinedByString:@","]; NSLog(@"joinString = %@",joinString); //7.访问数组最后一个元素 NSString *lastObj = [array4 lastObject]; //array4.lastObject NSLog(@"lsatObj = %@",lastObj); //8.再原路的数组后面添加一个元素 NSArray *array5 = [array4 arrayByAddingObject:@"zhaolia"]; NSLog(@"array5 = %@",array5); //取对应下标元素 int idx=4; if (idx <array5.count) { NSString *s = [array5 objectAtIndex:idx]; NSLog(@"s = %@",s); } //--------------数组的遍历 //1.普通遍历 for (int i=0; i<array5.count; i++) { NSString *str = [array5 objectAtIndex:i]; NSLog(@"%@",str); } //快速遍历 for (NSString *s in array5) { NSLog(@"%@",s); } //4.4之后的优化 //1.创建一个素组 NSArray *array7 = @[s1,s2,s3]; //等价于:NSArray *array7 = [NSArray arrayWithObjects:s1,s2,s3,nil]; NSLog(@"array7 = %@",array7); NSString *str = array7[0]; NSLog(@"array[7] = %@",str); //------------------可变数组 //初始化,设定元素个数为5,可以更改的。(继承自NSArray) NSMutableArray *mutableArray = [NSMutableArray arrayWithCapacity:5]; //想数组中添加一个元素 [mutableArray addObject:@"aaa"]; //向数组中指定下标插入元素 [mutableArray insertObject:@"ccc" atIndex:0]; NSLog(@"%@",mutableArray); //原来位置元素后移 //移除最后一个元素 [mutableArray removeLastObject]; NSLog(@"移除最后元素后:%@",mutableArray); //移除指定元素 [mutableArray removeObject:@"aaa"]; //移除指定下标元素 [mutableArray removeObjectAtIndex:0]; //向数组中添加数组 [mutableArray addObjectsFromArray:array1]; //1.创建可变数组 NSString *t1 = @"zhangsan "; NSString *t2 = @"lisi"; NSString *t3 = @"wangwu "; // NSMutableArray *mArray1 = @[s1,s2,s3];//wrong.这里创建了一个不可变数组 NSMutableArray *mArray1 = [[NSMutableArray alloc] initWithObjects:s1,s2,s3, nil]; //创建数组时,开辟3个空间用于存储元素,存储超过容量,数组自动增大空间 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); //将mArray2 中元素添加到mArray3中 // [mArray3 addObjectsFromArray:mArray2]; //将mArray2作为二维数字添加 [mArray3 addObject:mArray2]; NSLog(@"mArray3 = %@",mArray3); //3.插入元素 [mArray2 insertObject:@"Jack" atIndex:0]; NSLog(@"mArray2 = %@",mArray2); //4.替换元素 [mArray2 replaceObjectAtIndex:0 withObject:@"John"]; NSLog(@"替换:%@",mArray2); //5.互换两个元素的位置 [mArray2 exchangeObjectAtIndex:3 withObjectAtIndex:0]; NSLog(@"mArray2 = %@",mArray2); //6.删除元素 //6.1根据下标删除 [mArray2 removeObjectAtIndex:2]; NSLog(@"mArray2 = %@",mArray2); //6.2删除最后一个元素 [mArray2 removeLastObject]; NSLog(@"mArray2 = %@",mArray2); //6.3删除指定的对象 //[mArray2 removeObject:@"zhangsan"]; //6.4删除所有元素 [mArray2 removeAllObjects]; NSLog(@"mArray2 = %@",mArray2);
以上所述是小编给大家介绍的iOS中NSArray数组常用处理方式,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对我们网站的支持!
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