iOS 基础集合类
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本文参阅 objc.io 文章 http://www.objc.io/issue-7/collections.html 而进行的总结。全文中文翻译：http://www.cocoachina.com/applenews/devnews/2014/0122/7735.html
测试环境设置： xcode5 ios7 64位 编译设置release为-Ofast；Vectorize loops and unroll loops 设置关闭
1、集合类一般都有两个版本：可变类型和不可变类型。其中不可变类型是完全线程安全的，而可变类型不能保证这一点。所以在API接口中，不应该返回可变类型的集合参数。有时候更有效的做法是：在程序内部保持一个可变类型的集合类对象，而返回一个复制的，不可变类型的集合类对象以供外部访问。
2、NSArray
①缩写的创建语法格式
//这两种创建 NSArray 的方式是相同的
NSArray *array_1 = @[@"hello",@"world"];
NSArray *array_2 = [NSArray arrayWithObjects:@"hello",@"world", nil];
②NSArray的对集合元素的下标操作
//这两种方式获取 NSArray 中元素是相同的
NSLog(@"print = %@",array_1[0]);
NSLog(@"print = %@",[array_1 objectAtIndex:0]);
③在通过对一个array复制来创建一个可变数组的时候，由于源数组array可能为nil，所以创建的时候要考虑到nil的情况。
其正确的创建方式有：
NSArray *array = @[@"string1",@"string2"];
//方式1
NSMutableArray *mutableArray_1 = [array mutableCopy];
if (!mutableArray_1) {
mutableArray_1 = [NSMutableArray array];
}
//通过 三元运算符 ?: 简化方式1的写法
NSMutableArray *mutableArray_2 = [array mutableCopy]?:[NSMutableArray array];
//方式2
NSMutableArray *mutableArray_3 = [NSMutableArray arrayWithArray:array];
④对于创建NSMatableArray，介于代码的可读性，不要使用 NSMutableArray *mutableArray = [ @[] mutableCopy ]; 这种方式创建；而要采用
NSArray *array = @[@"John Appleseed", @"Tim Cook", @"Hair Force One", @"Michael Jurewitz"];
NSArray *sortedArray = [array sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
[sortedArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSLog(@"%zi --- %@",idx,obj);
}];
NSArray *numbers = @[@9, @5, @11, @3, @1];
NSArray *sortedNumbers = [numbers sortedArrayUsingSelector:@selector(compare:)];
[sortedNumbers enumerateObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSLog(@"%zi --- %@",idx,obj);
}];
输出结果：
2014-01-24 10:26:24.270 Foundation[871:303] 0 --- Hair Force One 2014-01-24 10:26:24.273 Foundation[871:303] 1 --- John Appleseed 2014-01-24 10:26:24.275 Foundation[871:303] 2 --- Michael Jurewitz 2014-01-24 10:26:24.276 Foundation[871:303] 3 --- Tim Cook 2014-01-24 10:26:24.277 Foundation[871:303] 0 --- 1 2014-01-24 10:26:24.277 Foundation[871:1003] 1 --- 3 2014-01-24 10:26:24.277 Foundation[871:1907] 2 --- 5 2014-01-24 10:26:24.280 Foundation[871:303] 3 --- 9 2014-01-24 10:26:24.280 Foundation[871:1003] 4 --- 11
#import <Foundation/Foundation.h> @interface Person : NSObject @property(nonatomic,strong)NSString* name; @property(nonatomic)int age; -(void)sortArray; @end
#import "Person.h"
@implementation Person
+(Person*)personWithAge:(int)age withName:(NSString*)name
{
Person* person = [[Person alloc]init];
person.age = age;
person.name = name;
return person;
}
//自定义排序方法
-(NSComparisonResult)comparePerson:(Person *)person{
//默认按年龄排序
NSComparisonResult result = [[NSNumber numberWithInt:person.age] compare:[NSNumber numberWithInt:self.age]];
//注意:基本数据类型要进行数据转换
//如果年龄一样，就按照名字排序
if (result == NSOrderedSame) {
result = [self.name compare:person.name];
}
return result;
}
-(void)sortArray
{
Person *p1 = [Person personWithAge:23 withName:@"zhangsan"];
Person *p2 = [Person personWithAge:21 withName:@"lisi"];
Person *p3 = [Person personWithAge:24 withName:@"wangwu"];
Person *p4 = [Person personWithAge:24 withName:@"liwu"];
Person *p5 = [Person personWithAge:20 withName:@"liwu"];
NSArray *array = [NSArray arrayWithObjects:p1,p2,p3,p4,p5, nil];
NSArray *sortedArray = [array sortedArrayUsingSelector:@selector(comparePerson:)];
[sortedArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSLog(@"%zi --- %@ --- %d",idx,[obj name],[obj age]);
}];
}
@end
调用执行 sortArray 方法。
2014-01-24 10:59:55.417 Foundation[1234:303] 0 --- liwu --- 24 2014-01-24 10:59:55.422 Foundation[1234:303] 1 --- wangwu --- 24 2014-01-24 10:59:55.424 Foundation[1234:303] 2 --- zhangsan --- 23 2014-01-24 10:59:55.425 Foundation[1234:303] 3 --- lisi --- 21 2014-01-24 10:59:55.425 Foundation[1234:303] 4 --- liwu --- 20注意到上面排序结果中是年龄是降序的，那么如果想要是升序结果的话，需要修改的地方是：
NSComparisonResult result = [[NSNumber numberWithInt:self.age] compare:[NSNumber numberWithInt:person.age]];
-(void)sortArray_1
{
Person *p1 = [Person personWithAge:23 withName:@"zhangsan"];
Person *p2 = [Person personWithAge:21 withName:@"lisi"];
Person *p3 = [Person personWithAge:24 withName:@"wangwu"];
Person *p4 = [Person personWithAge:24 withName:@"liwu"];
Person *p5 = [Person personWithAge:20 withName:@"liwu"];
NSArray *array = [NSArray arrayWithObjects:p1,p2,p3,p4,p5, nil];
NSArray *sortedArray = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
NSComparisonResult result = [[NSNumber numberWithInt:[obj1 age]] compare:[NSNumber numberWithInt:[obj2 age]]];
if (result == NSOrderedSame) {
result = [[obj1 name] compare:[obj2 name]];
}
return result;
}];
[sortedArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSLog(@"%zi --- %@ --- %d",idx,[obj name],[obj age]);
}];
}
运行输出结果：
2014-01-24 13:09:24.963 Foundation[1581:303] 0 --- liwu --- 20 2014-01-24 13:09:24.968 Foundation[1581:303] 1 --- lisi --- 21 2014-01-24 13:09:24.968 Foundation[1581:303] 2 --- zhangsan --- 23 2014-01-24 13:09:24.969 Foundation[1581:303] 3 --- liwu --- 24 2014-01-24 13:09:24.970 Foundation[1581:303] 4 --- wangwu --- 24
#import "Car.h"
@implementation Car
+(Car *)initWithName:(NSString *)name{
Car *car = [Car alloc] init];
car.name = name;
return car;
}
@end
在Person类中添加一个Car对象。
+(Person *)personWithAge:(int)age withName:(NSString *)name withCar:(Car *)car{
Person *person = [[Person alloc] init];
person.age = age;
person.name = name;
person.car = car;
return person;
}
-(void)sortArray_2
{
//首先来3辆车，分别是奥迪、劳斯莱斯、宝马
Car *car1 = [Car initWithName:@"Audio"];
Car *car2 = [Car initWithName:@"Rolls-Royce"];
Car *car3 = [Car initWithName:@"BMW"];
//再来5个Person，每人送辆车，分别为car2、car1、car1、car3、car2
Person *p1 = [Person personWithAge:23 withName:@"zhangsan" withCar:car2];
Person *p2 = [Person personWithAge:21 withName:@"zhangsan" withCar:car1];
Person *p3 = [Person personWithAge:24 withName:@"lisi" withCar:car1];
Person *p4 = [Person personWithAge:23 withName:@"wangwu" withCar:car3];
Person *p5 = [Person personWithAge:23 withName:@"wangwu" withCar:car2];
//加入数组
NSArray *array = [NSArray arrayWithObjects:p1,p2,p3,p4,p5, nil];
//构建排序描述器
NSSortDescriptor *carNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"car.name" ascending:YES];
NSSortDescriptor *personNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES];
NSSortDescriptor *personAgeDesc = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:YES];
//把排序描述器放进数组里，放入的顺序就是你想要排序的顺序
//我这里是：首先按照年龄排序，然后是车的名字，最后是按照人的名字
NSArray *descriptorArray = [NSArray arrayWithObjects:personAgeDesc,carNameDesc,personNameDesc, nil];
NSArray *sortedArray = [array sortedArrayUsingDescriptors: descriptorArray];
[sortedArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSLog(@"%zi --- %@ --- %d --- %@",idx,[obj name],[obj age],[[obj car] name]);
}];
}
运行输出结果:
2014-01-24 13:04:06.008 Foundation[1552:303] 0 --- zhangsan --- 21 --- Audio 2014-01-24 13:04:06.012 Foundation[1552:303] 1 --- wangwu --- 23 --- BMW 2014-01-24 13:04:06.013 Foundation[1552:303] 2 --- wangwu --- 23 --- Rolls-Royce 2014-01-24 13:04:06.014 Foundation[1552:303] 3 --- zhangsan --- 23 --- Rolls-Royce 2014-01-24 13:04:06.016 Foundation[1552:303] 4 --- lisi --- 24 --- Audio
NSArray *array = @[@"string1",@"string2",@"string3"];
//方式一：普通的for循环
for (int i=0; i < [array count]; i++) {
NSLog(@"%zi --- %@",i,[array objectAtIndex:i]);
}
//方式二：快输for循环
for (id obj in array) {
NSLog(@"%zi --- %@",[array indexOfObject:obj],obj);
}
//方式三：使用block
//1: enumerateObjectsUsingBlock 正序遍历
[array enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSLog(@"%zi --- %@",idx,obj);
}];
//2: enumerateObjectsUsingBlock 正序遍历：NSEnumerationConcurrent 反序遍历：NSEnumerationReverse
[array enumerateObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSLog(@"%zi --- %@",idx,obj);
}];
[array enumerateObjectsWithOptions:NSEnumerationReverse usingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSLog(@"%zi --- %@",idx,obj);
}];
//方式四：利用枚举
NSEnumerator* en = [array objectEnumerator];
id obj = NULL;
while (obj = [en nextObject]) {
NSLog(@"%zi --- %@",[array indexOfObject:obj],obj);
}
4、二分查找（要求数组已经排序）
typedef NS_OPTIONS(NSUInteger, NSBinarySearchingOptions) {
NSBinarySearchingFirstEqual = (1UL << 8),
NSBinarySearchingLastEqual = (1UL << 9),
NSBinarySearchingInsertionIndex = (1UL << 10),
};
- (NSUInteger)indexOfObject:(id)obj
inSortedRange:(NSRange)r
options:(NSBinarySearchingOptions)opts
usingComparator:(NSComparator)cmp;
用法示例：
NSArray *sortedArray = ... // must be sorted
id searchObject = ...
NSRange searchRange = NSMakeRange(0, [sortedArray count]);
NSUInteger findIndex = [sortedArray indexOfObject:searchObject
inSortedRange:searchRange
options:NSBinarySearchingFirstEqual
usingComparator:^(id obj1, id obj2)
{
return [obj1 compare:obj2];
}];
5、枚举数组 Enumeration
// First variant, using `indexesOfObjectsWithOptions:passingTest:`.
NSIndexSet *indexes = [randomArray indexesOfObjectsWithOptions:NSEnumerationConcurrent
passingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
return testObj(obj);
}];
NSArray *filteredArray = [randomArray objectsAtIndexes:indexes];
// Filtering using predicates (block-based or text)
NSArray *filteredArray2 = [randomArray filteredArrayUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(id obj, NSDictionary *bindings) {
return testObj(obj);
}]];
// Block-based enumeration
NSMutableArray *mutableArray = [NSMutableArray array];
[randomArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
if (testObj(obj)) {
[mutableArray addObject:obj];
}
}];
// Classic enumeration
NSMutableArray *mutableArray = [NSMutableArray array];
for (id obj in randomArray) {
if (testObj(obj)) {
[mutableArray addObject:obj];
}
}
// Using NSEnumerator, old school.
NSMutableArray *mutableArray = [NSMutableArray array];
NSEnumerator *enumerator = [randomArray objectEnumerator];
id obj = nil;
while ((obj = [enumerator nextObject]) != nil) {
if (testObj(obj)) {
[mutableArray addObject:obj];
}
}
// Using objectAtIndex: (via subscripting)
NSMutableArray *mutableArray = [NSMutableArray array];
for (NSUInteger idx = 0; idx < randomArray.count; idx++) {
id obj = randomArray[idx];
if (testObj(obj)) {
[mutableArray addObject:obj];
}
}
| Enumeration Method / Time [ms] | 10.000.000 elements | 10.000 elements |
|---|---|---|
indexesOfObjects:, concurrent
|
1844.73 | 2.25 |
NSFastEnumeration (for in)
|
3223.45 | 3.21 |
indexesOfObjects:
|
4221.23 | 3.36 |
enumerateObjectsUsingBlock:
|
5459.43 | 5.43 |
objectAtIndex:
|
5282.67 | 5.53 |
NSEnumerator
|
5566.92 | 5.75 |
filteredArrayUsingPredicate:
|
6466.95 | 6.31 |
//创建 字典 的两种方式
NSDictionary *dic_1 = [NSDictionary dictionaryWithObjectsAndKeys:@"value",@"key",@"value2",@"key2", nil];
NSDictionary *dic_2 = @{@"key": @"value",@"key2":@"value2"};
//根据key访问value的两种方式
NSLog(@"%@",[dic_1 objectForKey:@"key"]);
NSLog(@"%@",dic_1[@"key"]);
7、枚举字典
// Using keysOfEntriesWithOptions:passingTest:,optionally concurrent
NSSet *matchingKeys = [randomDict keysOfEntriesWithOptions:NSEnumerationConcurrent
passingTest:^BOOL(id key, id obj, BOOL *stop)
{
return testObj(obj);
}];
NSArray *keys = matchingKeys.allObjects;
NSArray *values = [randomDict objectsForKeys:keys notFoundMarker:NSNull.null];
__unused NSDictionary *filteredDictionary = [NSDictionary dictionaryWithObjects:values
forKeys:keys];
// Block-based enumeration.
NSMutableDictionary *mutableDictionary = [NSMutableDictionary dictionary];
[randomDict enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
if (testObj(obj)) {
mutableDictionary[key] = obj;
}
}];
// NSFastEnumeration
NSMutableDictionary *mutableDictionary = [NSMutableDictionary dictionary];
for (id key in randomDict) {
id obj = randomDict[key];
if (testObj(obj)) {
mutableDictionary[key] = obj;
}
}
// NSEnumeration
NSMutableDictionary *mutableDictionary = [NSMutableDictionary dictionary];
NSEnumerator *enumerator = [randomDict keyEnumerator];
id key = nil;
while ((key = [enumerator nextObject]) != nil) {
id obj = randomDict[key];
if (testObj(obj)) {
mutableDictionary[key] = obj;
}
}
// C-based array enumeration via getObjects:andKeys:
NSMutableDictionary *mutableDictionary = [NSMutableDictionary dictionary];
id __unsafe_unretained objects[numberOfEntries];
id __unsafe_unretained keys[numberOfEntries];
[randomDict getObjects:objects andKeys:keys];
for (int i = 0; i < numberOfEntries; i++) {
id obj = objects[i];
id key = keys[i];
if (testObj(obj)) {
mutableDictionary[key] = obj;
}
}
| Filtering/Enumeration Method | Time [ms], 50.000 elements | 1.000.000 elements |
|---|---|---|
keysOfEntriesWithOptions:, concurrent
|
16.65 | 425.24 |
getObjects:andKeys:
|
30.33 | 798.49* |
keysOfEntriesWithOptions:
|
30.59 | 856.93 |
enumerateKeysAndObjectsUsingBlock:
|
36.33 | 882.93 |
NSFastEnumeration
|
41.20 | 1043.42 |
NSEnumeration
|
42.21 | 1113.08 |
一.不可变集合NSSet
1.NSSet的初始化
创建一个集合
NSSet *set1 = [[NSSet alloc] initWithObjects:@"one", @"two", nil];
通过数组的构建集合
NSArray *array = [NSArrayWithObjects:@"1", @"2", @"3", nil];
NSSet *set2 = [[NSSet alloc] initWithArray:array];
通过已有集合构建集合
NSSet *set3 = [[NSSet alloc] initWithSet:set2];
2.NSSet常用方法
集合中对象的个数
int count = [set3 count];
以数组的形式返回集合中所有的对象
NSArray *allObjects = [set3 allObjects];
返回集合中的任意一个对象
id object = [set3 anyObject];
判断两个集合的元素中有包含的对象，包含返回YES，否则为NO
BOOL isContain = [set4 containsObject:@"2"];
判断两个集合的元素是否有相等的对象，存在返回YES，否则为NO
BOOL isIntersect = [set4 intersectsSet:set2];
判断两个集合的元素是否完全匹配，匹配返回YES，否则为NO
BOOL isEqual = [set4 isEqualToSet:set5];
集合4是否是集合5的子集合，如果是返回YES，否则为NO
BOOL isSubset = [set4 isSubsetOfSet:set5];
创建一个新的集合2，集合2有两个对象
NSSet *set1 = [NSSet setWithObjects:@"a",nil];
NSSet *set2 = [set1 setByAddingObject:@"b"];
通过已有的两个集合，创建新的一个集合
NSSet *set7 = [NSSet setWithObjects:@"a",nil];
NSSet *set8 = [NSSet setWithObjects:@"z",nil];
NSSet *set9 = [set7 setByAddingObjectsFromSet:set8];
通过已有的集合和数组对象，创建一个新的集合
NSArray *array = [NSArray arrayWithObjects:@"a",@"b",@"c",nil];
NSSet *set10 = [NSSet setWithObjects:@"z",nil];
NSSet *set11 = [set10 setByAddingObjectsFromArray:array];
二、可变集合NSMutableSet
常用方法
创建一个空的集合
NSMutableSet *set1 = [NSMutableSet set];
NSMutableSet *set2 = [NSMutableSet setWithObjects:@"1",@"2",nil]；
NSMutableSet *set3 = [NSMutableSet setWithObjects:@"a",@"2",nil];
集合2减去集合3中的元素，集合2最后元素只有1个
[set2 minusSet:set3];
集合2与集合3中元素的交集，集合2最后元素只有1个
[set2 intersectSet:set3];
集合2与集合3中的元素的并集，集合2最后元素只有3个
[set2 unionSet:set3];
将空集合1设置为集合3中的内容
[set1 setSet:set3];
根据数组的内容删除集合中的对象
[set2 addObjectsFromArray:array];
[set2 removeObject:@"1"];
[set]2 removeAllObjects];
NSUInteger
is
either in the index set or isn’t. If you need to store an arbitrary number of integers that are not unique, better use an
NSArray
.
NSIndexSet *PSPDFIndexSetFromArray(NSArray *array) {
NSMutableIndexSet *indexSet = [NSMutableIndexSet indexSet];
for (NSNumber *number in array) {
[indexSet addIndex:[number unsignedIntegerValue]];
}
return [indexSet copy];
}
使用block语法从NSIndexSet中获取索引：
NSArray *PSPDFArrayFromIndexSet(NSIndexSet *indexSet) {
NSMutableArray *indexesArray = [NSMutableArray arrayWithCapacity:indexSet.count];
[indexSet enumerateIndexesUsingBlock:^(NSUInteger idx, BOOL *stop) {
[indexesArray addObject:@(idx)];
}];
return [indexesArray copy];
}
原文：http://blog.csdn.net/crayondeng/article/details/18727841
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