NSArray & NSMutableArray
1.NSArray(和java中的數組類似)
1)NSArray的創建,Foundation所有的類都能通過靜態方法創建,靜態創建類自動管理內存,一般都是以類名開頭。比如:
// 創建一個空的數組
NSArray *array = [NSArray array];
// 創建有1個元素的數組
array = [NSArray arrayWithObject:@"123"];
// 創建有多個元素的數組
array = [NSArray arrayWithObjects:@"a", @"b", @"c", nil];
//array長度
int count = [array count];
2)NSArray的簡單使用,NSArray只能添加objc對象,不能添加nil,基本類型,struct。如果要添加基本類型,可以通過NSNumber把基本類型轉化爲objc對象
#pragma mark 數組的簡單使用
void arrayUse() {
NSObject *obj = [[NSObject alloc] init];
NSArray *array = [NSArray arrayWithObjects:@"a", @"b", @"c" , obj, nil];
// 判斷是否包含了某個元素
if ([array containsObject:@"a"]) {
NSLog(@"包含了字符串a");
}
NSString *last = [array lastObject];
NSLog(@"last=%@", last);
NSString *str = [array objectAtIndex:1];
NSLog(@"%@", str);
int index = [array indexOfObject:@"c"];
NSLog(@"index=%i", index);
[obj release];
}
3)NSArray的內存管理,當把一個對象塞進數組中時,這個對象的計數器會加1,也就是說數組會對它做一次retain操作;數組被銷燬的時候,會對內部的所有 元素都做一次release操作
#pragma mark 數組的內存管理
void arrayMemory() {
// 1
Student *stu1 = [[Student alloc] init];
Student *stu2 = [[Student alloc] init];
Student *stu3 = [[Student alloc] init];
NSLog(@"stu1:%zi", [stu1 retainCount]);
// 當把一個對象塞進數組中時,這個對象的計數器會加1,也就是說數組會對它做一次retain操作
// 2
NSArray *array = [[NSArray alloc] initWithObjects:stu1, stu2, stu3, nil];
NSLog(@"stu1:%zi", [stu1 retainCount]);
NSLog(@"count=%zi", array.count);
// 1
[stu1 release];
[stu2 release];
[stu3 release];
// 數組被銷燬的時候,會對內部的所有元素都做一次release操作
// 0
[array release];
}
4)NSArray給數組元素髮消息,也就是調用數組元素的方法
#pragma mark 給數組裏面的元素髮送消息
void arrayMessage() {
Student *stu1 = [Student student];
Student *stu2 = [Student student];
Student *stu3 = [Student student];
NSArray *array = [NSArray arrayWithObjects:stu1, stu2, stu3, nil];
// 讓數組裏面的所有對象都調用test方法
// [array makeObjectsPerformSelector:@selector(test)];
[array makeObjectsPerformSelector:@selector(test2:) withObject:@"123"];
}
5)NSArray 遍歷數組 ,遍歷方法有 for循環,迭代器(NSEnumerator) 和 Block
//=========== 方法1 for=================
Student *stu1 = [Student student];
NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil];
// 快速遍歷
int i =0;
for (id obj in array) {
NSLog(@"%i-%@", i, obj);
i++;
}
//==========方法2 block=================
[array enumerateObjectsUsingBlock:
^(id obj, NSUInteger idx, BOOL *stop) {
NSLog(@"%i-%@", idx, obj);
// 如果索引爲1,就停止遍歷
if (idx == 1) {
// 利用指針修改外面BOOL變量的值
*stop = YES;
}
}];
//===========方法3NSEnumerator============
// 獲取數組的迭代器
// 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對象
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);
}
6)NSArray 派生出新的數組
#pragma mark 派生出新的數組
void arrayNew() {
NSArray *array = [NSArray arrayWithObjects:@"1", @"2", nil];
NSArray *array2 = [array arrayByAddingObject:@"3"];
NSArray *array3 = [array arrayByAddingObjectsFromArray:[NSArray arrayWithObjects:@"4", @"5", nil]];
NSLog(@"array:%@", array);
NSLog(@"array2:%@", array2);
NSLog(@"array3:%@", array3);
NSArray *array4 = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil];
NSRange range = NSMakeRange(1, 2);
NSArray *array5 = [array4 subarrayWithRange:range];
NSLog(@"array5:%@", array5);
}
7)NSArray 利用分隔符-拼接所有的數組元素,寫入文件,讀取文件(格式一定要是NSArray標準格式)
#pragma mark 數組的其他用法
void arrayOther() {
NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil];
// 1-2-3-4
// 利用分隔符-拼接所有的數組元素
NSString *str = [array componentsJoinedByString:@"-"];
NSLog(@"%@", str);
// 將一個數組寫入文件(生成的是一個xml文件)
NSString *path = @"/Users/apple/Desktop/array.xml";
[array writeToFile:path atomically:YES];
path = @"/Users/apple/Desktop/array.txt";
// 從文件中讀取數組內容(文件有嚴格的格式要求)
NSArray *array2 = [NSArray arrayWithContentsOfFile:path];
NSLog(@"array2:%@", array2);
}
8)NSArray排序,如果是數組的元素實現了 compare方法則定元素的比較方法:compare: 如果是比較自己定義的類,則要首先定義比較器
如:
(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 數組排序1
void arraySort1() {
NSArray *array = [NSArray arrayWithObjects:@"2", @"3", @"1", @"4", nil];
// 返回一個排好序的數組,原來數組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 數組排序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);
}
#pragma mark 數組排序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 數組排序4-高級排序
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
// 這裏的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];
// 按順序添加排序描述器
NSArray *descs = [NSArray arrayWithObjects:bookNameDesc, lastnameDesc, firstnameDesc, nil];
NSArray *array2 = [array sortedArrayUsingDescriptors:descs];
NSLog(@"array2:%@", array2);
}
2.NSArray是一個不可變數組,如果要對數組增刪改查,則需要用NSArray子類(NSMutableArray)
1)NSMutableArray基本用法增刪改查,其他用法跟NSArray一樣
void arrayCreate() {
NSMutableArray *array = [NSMutableArray arrayWithObject:@"1"];
// 添加元素
[array addObject:@"2"];
[array addObject:@"3"];
// [array removeObject:@"2"];
// [array removeLastObject];
[array removeAllObjects];
NSLog(@"%@", array);
//把1中元素替換爲@“4”
[array replaceObjectAtIndex:1 withObject:@"4"];
}