ios陣列基本用法和排序
阿新 • • 發佈:2019-01-08
1.建立陣列
// 建立一個空的陣列 NSArray *array = [NSArray array]; // 建立有1個元素的陣列 array = [NSArray arrayWithObject:@"123"]; // 建立有多個元素的陣列 array = [NSArray arrayWithObjects:@"a", @"b", @"c", nil]; NSArray *array3 = [array arrayByAddingObjectsFromArray:[NSArray arrayWithObjects:@"4", @"5", nil]]; NSArray *array4 = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil]; NSRange range = NSMakeRange(1, 2); NSArray *array5 = [array4 subarrayWithRange:range];
2.陣列的一些基本方法
int count = [array count];//個數 // 判斷是否包含了某個元素 if ([array containsObject:@"a"]) { NSLog(@"包含了字串a"); } NSString *last = [array lastObject];最後一個元素 NSString *str = [array objectAtIndex:1];根據索引獲取陣列中的元素 int index = [array indexOfObject:@"c"];獲取指定元素的索引 // 讓數組裡面的所有物件都呼叫test方法,123為引數 NSArray *array = [NSArray arrayWithObjects:stu1, stu2, stu3, nil]; [array makeObjectsPerformSelector:@selector(test2:) withObject:@"123"]; NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil]; // 1-2-3-4 // 利用分隔符-拼接所有的陣列元素 NSString *str = [array componentsJoinedByString:@"-"]; // 將一個數組寫入檔案(生成的是一個xml檔案) NSString *path = @"/Users/apple/Desktop/array.xml"; [array writeToFile:path atomically:YES]; path = @"/Users/apple/Desktop/array.txt"; // 從檔案中讀取陣列內容(檔案有嚴格的格式要求) NSArray *array2 = [NSArray arrayWithContentsOfFile:path];
3.遍歷陣列
#pragma mark 遍歷陣列1 void arrayFor1() { NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil]; int count = array.count; for (int i = 0; i<count; i++) { id obj = [array objectAtIndex:i]; } } #pragma mark 遍歷陣列2 快速遍歷 void arrayFor2() { Student *stu1 = [Student student]; NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil]; int i =0; for (id obj in array) { NSLog(@"%i-%@", i, obj); i++; } } #pragma mark 遍歷陣列3 void arrayFor3() { Student *stu1 = [Student student]; NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil]; [array enumerateObjectsUsingBlock: ^(id obj, NSUInteger idx, BOOL *stop) { NSLog(@"%i-%@", idx, obj); // 如果索引為1,就停止遍歷 if (idx == 1) { // 利用指標修改外面BOOL變數的值 *stop = YES; } }]; } #pragma mark 遍歷陣列4 void arrayFor4() { Student *stu1 = [Student student]; NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil]; // 獲取陣列的迭代器 // NSEnumerator *enumerator = [array objectEnumerator]; // 反序迭代器(從尾部開始遍歷元素) NSEnumerator *enumerator = [array reverseObjectEnumerator]; // allObjects是取出沒有被遍歷過的物件 NSArray *array2 = [enumerator allObjects]; NSLog(@"array2:%@", array2); // 獲取下一個需要遍歷的元素 id obj = nil; while (obj = [enumerator nextObject]) { NSLog(@"obj=%@", obj); } }
4.陣列排序
#pragma mark 陣列排序1
void arraySort1() {
NSArray *array = [NSArray arrayWithObjects:@"2", @"3", @"1", @"4", nil];
// 返回一個排好序的陣列,原來陣列的元素順序不會改變
// 指定元素的比較方法:compare:
NSArray *array2 = [array sortedArrayUsingSelector:@selector(compare:)];
NSLog(@"array2:%@", array2);
}
#pragma mark 陣列排序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];
// 指定排序的比較方法
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,就比較名字
if (result == NSOrderedSame) {
result = [self.firstname compare:stu.firstname];
}
return result;
}
#pragma mark 陣列排序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];
// 利用block進行排序
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,就比較名字
if (result == NSOrderedSame) {
result = [obj1.firstname compare:obj2.firstname];
}
return result;
}];
NSLog(@"array2:%@", array2);
}
#pragma mark 陣列排序4-高階排序
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];
// 1.先按照書名進行排序
// 這裡的key寫的是@property的名稱
NSSortDescriptor *bookNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"book.name" ascending:YES];
// 2.再按照姓進行排序
NSSortDescriptor *lastnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"lastname" ascending:YES];
// 3.再按照名進行排序
NSSortDescriptor *firstnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"firstname" ascending:YES];
// 按順序新增排序描述器
NSArray *descs = [NSArray arrayWithObjects:bookNameDesc, lastnameDesc, firstnameDesc, nil];
NSArray *array2 = [array sortedArrayUsingDescriptors:descs];
NSLog(@"array2:%@", array2);
}