ios数组基本用法和排序

1.创建数组

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// 创建一个空的数组

NSArray *array = [NSArray array];

// 创建有1个元素的数组

array = [NSArray arrayWithObject:@"123"];

// 创建有多个元素的数组

array = [NSArray arrayWithObjects:@"a", @"b", @"c", nil nil];

NSArray *array3 = [array arrayByAddingObjectsFromArray:[NSArray arrayWithObjects:@"4", @"5", nil nil]];

NSArray *array4 = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil nil];

NSRange range = NSMakeRange(1, 2);

NSArray *array5 = [array4 subarrayWithRange:range];

2.数组的一些基本方法

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int count = [array count];//个数

// 判断是否包含了某个元素

if ([array containsObject:@"a"]) {

NSLog(@"包含了字符串a");

}

NSString *last = [array lastObject];最后一个元素

NSString *str = [array objectAtIndex:1];根据索引获取数组中的元素

int index = [array indexOfObject:@"c"];获取指定元素的索引

// 让数组里面的所有对象都调用test方法，123为参数

NSArray *array = [NSArray arrayWithObjects:stu1, stu2, stu3, nil nil];

[array makeObjectsPerformSelector:@selector(test2:) withObject:@"123"];

NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil nil];

// 1-2-3-4

// 利用分隔符-拼接所有的数组元素

NSString *str = [array componentsJoinedByString:@"-"];

// 将一个数组写入文件（生成的是一个xml文件）

NSString *path = @"/Users/apple/Desktop/array.xml";

[array writeToFile:path atomically:YES];

path = @"/Users/apple/Desktop/array.txt";

// 从文件中读取数组内容（文件有严格的格式要求）

NSArray *array2 = [NSArray arrayWithContentsOfFile:path];

3.遍历数组

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#pragma mark 遍历数组1

void arrayFor1() {

NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];

int count = array.count;

for (int i = 0; i<count; i++) {

id obj = [array objectAtIndex:i];

}

}

#pragma mark 遍历数组2 快速遍历

void arrayFor2() {

Student *stu1 = [Student student];

NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];

int i =0;

for (id obj in array) {

NSLog(@"%i-%@", i, obj);

i++;

}

}

#pragma mark 遍历数组3

void arrayFor3() {

Student *stu1 = [Student student];

NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];

[array enumerateObjectsUsingBlock:

^(id obj, NSUInteger idx, BOOLBOOL *stop) {

NSLog(@"%i-%@", idx, obj);

// 如果索引为1，就停止遍历

if (idx == 1) {

// 利用指针修改外面BOOL变量的值

*stop = YES;

}

}];

}

#pragma mark 遍历数组4

void arrayFor4() {

Student *stu1 = [Student student];

NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];

// 获取数组的迭代器

// NSEnumerator *enumerator = [array objectEnumerator];

// 反序迭代器（从尾部开始遍历元素）

NSEnumerator *enumerator = [array reverseObjectEnumerator];

// allObjects是取出没有被遍历过的对象

NSArray *array2 = [enumerator allObjects];

NSLog(@"array2:%@", array2);

// 获取下一个需要遍历的元素

id obj = nil;

while (obj = [enumerator nextObject]) {

NSLog(@"obj=%@", obj);

}

}

4.数组排序

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#pragma mark 数组排序1

void arraySort1() {

NSArray *array = [NSArray arrayWithObjects:@"2", @"3", @"1", @"4", nil nil];

// 返回一个排好序的数组，原来数组的元素顺序不会改变

// 指定元素的比较方法：compare:

NSArray *array2 = [array sortedArrayUsingSelector:@selector(compare:)];

NSLog(@"array2:%@", array2);

}

#pragma mark 数组排序2

void arraySort2() {

Student *stu1 = [Student studentWithFirstname:@"MingJie" lastname:@"Li"];

Student *stu2 = [Student studentWithFirstname:@"LongHu" lastname:@"Huang"];

Student *stu3 = [Student studentWithFirstname:@"LianJie" lastname:@"Li"];

Student *stu4 = [Student studentWithFirstname:@"Jian" lastname:@"Xiao"];

NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, stu4, nil nil];

// 指定排序的比较方法

NSArray *array2 = [array sortedArrayUsingSelector:@selector(compareStudent:)];

NSLog(@"array2:%@", array2);

}

- (NSComparisonResult)compareStudent:(Student *)stu {

// 先按照姓排序

NSComparisonResult result = [self.lastname compare:stu.lastname];

// 如果有相同的姓，就比较名字

if (result == NSOrderedSame) {

result = [self.firstname compare:stu.firstname];

}

return result;

}

#pragma mark 数组排序3

void arraySort3() {

Student *stu1 = [Student studentWithFirstname:@"MingJie" lastname:@"Li"];

Student *stu2 = [Student studentWithFirstname:@"LongHu" lastname:@"Huang"];

Student *stu3 = [Student studentWithFirstname:@"LianJie" lastname:@"Li"];

Student *stu4 = [Student studentWithFirstname:@"Jian" lastname:@"Xiao"];

NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, stu4, nil nil];

// 利用block进行排序

NSArray *array2 = [array sortedArrayUsingComparator:

^NSComparisonResult(Student *obj1, Student *obj2) {

// 先按照姓排序

NSComparisonResult result = [obj1.lastname compare:obj2.lastname];

// 如果有相同的姓，就比较名字

if (result == NSOrderedSame) {

result = [obj1.firstname compare:obj2.firstname];

}

return result;

}];

NSLog(@"array2:%@", array2);

}

#pragma mark 数组排序4-高级排序

void arraySort4() {

Student *stu1 = [Student studentWithFirstname:@"MingJie" lastname:@"Li" bookName:@"book1"];

Student *stu2 = [Student studentWithFirstname:@"LongHu" lastname:@"Huang" bookName:@"book2"];

Student *stu3 = [Student studentWithFirstname:@"LianJie" lastname:@"Li" bookName:@"book2"];

Student *stu4 = [Student studentWithFirstname:@"Jian" lastname:@"Xiao" bookName:@"book1"];

NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, stu4, nil nil];

// 1.先按照书名进行排序

// 这里的key写的是@property的名称

NSSortDescriptor *bookNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"book.name" ascending:YES];

// 2.再按照姓进行排序

NSSortDescriptor *lastnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"lastname" ascending:YES];

// 3.再按照名进行排序

NSSortDescriptor *firstnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"firstname" ascending:YES];

// 按顺序添加排序描述器

NSArray *descs = [NSArray arrayWithObjects:bookNameDesc, lastnameDesc, firstnameDesc, nil nil];

NSArray *array2 = [array sortedArrayUsingDescriptors:descs];

NSLog(@"array2:%@", array2);

}