Objective-C基础笔记（9)Foundation常用类NSArray

标签：objective-c   nsarray   排序   

NSArray用来存储对象的有序列表，它是不可变的

NSArray不能存储C语言中的基本数据类型，如int、float、enum、struct，也不能存储nil，nil代表数组元素的结束

//
//  main.m
//  NSArray
//
//  Created by lixiaoqiang on 14/11/19.
//  Copyright (c) 2014年 lixiaoqiang. All rights reserved.
//

#import <Foundation/Foundation.h>

//数组的创建
void arrayCreate(){
    //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,nil代表元素的结束
    array = [NSArray arrayWithObjects:@"a", @"b", @"c", nil];
    //查看元素个数
    int count = [array count]; //或者使用[array.count]
}

//数组的简单使用
void arrayUse(){
    NSArray *array = [NSArray arrayWithObjects:@"a", @"b", @"c", nil];
    //判断是否包含了某个元素
    if([array containsObject:@"a"]){
        NSLog(@"包含了子元素a");
    }
    //获取数组最后一个元素
    NSString *last = [array lastObject];
    NSLog(@"最后一个元素是%@", last);
    //获取某个索引处的元素
    NSString *str = [array objectAtIndex:1];
    NSLog(@"索引是1的位置是%@", str);
    //判读元素的索引
    unsigned long index = [array indexOfObject:@"c"];
    NSLog(@"c的位置索引是%zi", index);
}

//定义一个Student对象
@interface Student : NSObject
//添加两个属性
@property (nonatomic, retain) NSString *firstname;
@property (nonatomic, retain) NSString *lastname;

+ (id)student; //构造方法
+ (id)studentWithFirstName:(NSString *)firstname lastname:(NSString *)lastname;
- (void)test;
//用于对象比较（返回值必须是NSComparisonResult类型)
- (NSComparisonResult) compareStudent:(Student *)stu;

@end

@implementation Student

+ (id)student{
    return [[[Student alloc] init] autorelease];
}
+ (id)studentWithFirstName:(NSString *)firstname lastname:(NSString *)lastname {
    Student *stu = [[[Student alloc] init] autorelease];
    stu.firstname = firstname;
    stu.lastname = lastname;
    return stu;
}
- (void)test {
    NSLog(@"Student的test方法");
}

- (NSComparisonResult)compareStudent:(Student *)stu{
    //按照姓进行排序
    return [self.lastname compare:stu.lastname];
}

//相当于java的toString方法
- (NSString *)description{
    return [NSString stringWithFormat:@"[%@ %@]", self.lastname, self.firstname];
}

- (void)dealloc{
    NSLog(@"%@被销毁了");
    [_firstname release];
    [_lastname release];
    [super dealloc];
}
@end

//数组的内存管理
void arrayMemory(){
    Student *stu1 = [[Student alloc] init];
    Student *stu2 = [[Student alloc] init];
    Student *stu3 = [[Student alloc] init];
    NSLog(@"stu1:%zi", [stu1 retainCount]); //计数器为1
    //数组会对添加的对象做一次retain操作
    NSArray *array = [[NSArray alloc] initWithObjects:stu1, stu2, stu3, nil];
    NSLog(@"stu1:%zi", [stu1 retainCount]); //计数器为2
    NSLog(@"count=%zi", array.count);
    //数组被销毁的时候会对内部的所有元素都做一次release操作
    [array release];
    [stu1 release];
    [stu2 release];
    [stu3 release];
}

void arrayMessage(){
    Student *stu1 = [Student student];
    Student *stu2 = [Student student];
    Student *stu3 = [Student student];
    
    NSArray *array = [NSArray arrayWithObjects:stu1, stu2, stu3, nil];
    //让数组里面的所有对象调用test方法
    [array makeObjectsPerformSelector:@selector(test)];
}

//遍历数组1
void arrayFor1(){
    NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", nil];
    //id == void * 代表任何类型的指针变量
    int count = array.count;
    for(int i=0; i<count; i++){
        id obj = [array objectAtIndex:i];
        NSLog(@"%i位置是%@", i, obj);
    }
}

//遍历数组2
void arrayFor2(){
    NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", nil];
    for(id obj in array){
        NSLog(@"%@", obj);
    }
}

//遍历数组3----Block
void arrayFor3(){
    NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", nil];
    [array enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        NSLog(@"%Zi位置是%@", idx, obj);
        if(idx == 1) *stop = YES; //如果索引为1则停止遍历
    }];
}

//遍历数组4----迭代器
void arrayFor4(){
    NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", nil];
    //获取数组的迭代器
    NSEnumerator *enumerator = [array objectEnumerator];
    //反向迭代器
    //NSEnumerator *renu = [array reverseObjectEnumerator];
    //获取下一个遍历的元素
    //[enumerator nextObject];
    id obj = nil;
    while(obj = [enumerator nextObject]){
        NSLog(@"%@", obj);
    }
}

//派生出新的数组
void arrayNew(){
    //添加元素
    NSArray *array = [NSArray arrayWithObjects:@"1", @"2", nil];
    NSArray *array2 = [array arrayByAddingObject:@"3"];
    //裁剪元素
    NSRange range = NSMakeRange(1, 2);
    [array2 subarrayWithRange:range];
}

//数组的其他用法
void arrayOther(){
    //利用分隔符拼接
    NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil];
    NSString *str = [array componentsJoinedByString:@","];
    NSLog(@"%@", str); //1,2,3,4
    //数组写入文件
    NSArray *path = @"/user/apple/Desktop/array.xml";
    [array writeToFile:path atomically:YES];
    //从文件读出数组
    NSArray *array2 = [NSArray arrayWithContentsOfFile:path];
}

//数组排序1
void arraySort1(){
    NSArray *array = [NSArray arrayWithObjects:@"3", @"1", @"4", @"2", nil];
    //指定元素的比较方法(compare:)
    NSArray *array2 = [array sortedArrayUsingSelector:@selector(compare:)];
    NSLog(@"array2:%@", array2);
}

//数组排序2
void arraySort2(){
    Student *stu1 = [Student studentWithFirstName:@"sun" lastname:@"home"];
    Student *stu2 = [Student studentWithFirstName:@"dawan" lastname:@"ganban"];
    Student *stu3 = [Student studentWithFirstName:@"lxq" lastname:@"xsyu"];
    
    NSArray *array = [NSArray arrayWithObjects:stu1, stu2, stu3, nil];
    
    NSArray *array2 = [array sortedArrayUsingSelector:@selector(compareStudent:)];
}

//数组排序3---Block排序
void arraySort3(){
    Student *stu1 = [Student studentWithFirstName:@"sun" lastname:@"home"];
    Student *stu2 = [Student studentWithFirstName:@"dawan" lastname:@"ganban"];
    Student *stu3 = [Student studentWithFirstName:@"lxq" lastname:@"xsyu"];
    
    NSArray *array = [NSArray arrayWithObjects:stu1, stu2, stu3, nil];
    [array sortedArrayUsingComparator:^NSComparisonResult(Student *stu1, Student *stu2) {
        return [stu1.lastname compare:stu2.lastname];
    }];
}

//数组排序4，可以用来对对象嵌套排序 比如Student中有一个book对象就可以使用@"book.bookname"对书名排序
void arraySort4(){
    Student *stu1 = [Student studentWithFirstName:@"sun" lastname:@"home"];
    Student *stu2 = [Student studentWithFirstName:@"dawan" lastname:@"ganban"];
    Student *stu3 = [Student studentWithFirstName:@"lxq" lastname:@"xsyu"];
    //创建排序描述器
    NSSortDescriptor *descript = [NSSortDescriptor sortDescriptorWithKey:@"lastname" ascending:YES];
    NSArray *array = [NSArray arrayWithObjects:stu1, stu2, stu3, nil];
    //调用排序
    NSArray *array2 = [array sortedArrayUsingDescriptors:descript];
}

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        //arrayFor4();
    }
    return 0;
}

NSMutableArray是可变数组，派生自NSArray，相关操作如下

void arrayCreate(){
    NSMutableArray *array = [NSMutableArray arrayWithObjects:@"1", @"2", nil];
    [array addObject:@"3"];
    [array removeObject:@"3"];
    
    [array removeLastObject];
    [array removeAllObjects];
}

void arrayMemory(){
    //对被添加的元素做一次retain操作
    //[array addObject:stu1];
    //对被删除的元素做一次release操作
    //[array removeObject:stu1];
    
    //当数组被释放的时候会对所有的元素做一次release操作
    //[array release];
}

Objective-C基础笔记（9)Foundation常用类NSArray

标签：objective-c   nsarray   排序   

原文地址：http://blog.csdn.net/dawanganban/article/details/41356895