IOS开发数组的一些基本操作，遍历、排序

数组的一些基本方法

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];  

遍历数组

#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);  
    }  
}  

数组排序

#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);  
}