• OC复习


    //
    //  main.m
    //  oc复习
    //
    //  Created by User on 3/10/13.
    //  Copyright (c) 2013 User. All rights reserved.
    //
    
    #import <Foundation/Foundation.h>
    #import "Student.h"
    
    //创建一个数组
    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
        array = [NSArray arrayWithObjects:@"a", @"b", @"c", nil];
        // 数组的元素
        int count = [array count];
        // count = array.count;
        NSLog(@"%i", count);
    }
    
    #pragma mark 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(@"包含了字符串a");
        }
        //得到数组的最后一个元素
        NSString *last = [array lastObject];
        NSLog(@"last=%@", last);
        //得到索引为1的元素
        NSString *str = [array objectAtIndex:1];
        NSLog(@"%@", str);
        //得到元素c的索引
        int index = [array indexOfObject:@"c"];
        NSLog(@"index=%i", index);
    }
    
    #pragma mark 数组的内存管理
    void arrayMemory() {
        // 1
        Student *stu1 = [[Student alloc] init];
        Student *stu2 = [[Student alloc] init];
        Student *stu3 = [[Student alloc] init];
        NSLog(@"stu1:%zi", [stu1 retainCount]);
        // 当把一个对象塞进数组中时,这个对象的计数器会加1,也就是说数组会对它做一次retain操作
        // 2
        NSArray *array = [[NSArray alloc] initWithObjects:stu1, stu2, stu3, nil];
        NSLog(@"stu1:%zi", [stu1 retainCount]);
        // 1
        [stu1 release];
        [stu2 release];
        [stu3 release];
        // 数组被销毁的时候,会对内部的所有元素都做一次release操作
        // 0
        [array release];
    }
    
    //给数组里面的元素发送消息
    void arrayMessage() {
        Student *stu1 = [Student student];
        Student *stu2 = [Student student];
        Student *stu3 = [Student student];
        
        NSArray *array = [NSArray arrayWithObjects:stu1, stu2, stu3, nil];
        // 让数组里面的所有对象都调用test方法
        // [array makeObjectsPerformSelector:@selector(test)];
        [array makeObjectsPerformSelector:@selector(test2:) withObject:@"123"];
    }
    
    //遍历数组1
    void arrayFor1() {
        Student *stu1 = [Student student];
        NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil];
        int count = array.count;
        for (int i = 0; i<count; i++) {
            // id == void *
            id obj = [array objectAtIndex:i];
            NSLog(@"%i-%@", i, obj);
        }
    }
    
    //遍历数组2
    void arrayFor2() {
        Student *stu1 = [Student student];
        NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil];
        // 快速遍历
        int i =0;
        for (id obj in array) {
            NSLog(@"%i-%@", i, obj);
            i++;
        }
    }
    
    //遍历数组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;
             }
         }];
    }
    
    //遍历数组4
    void arrayFor4() {
        Student *stu1 = [Student student];
        NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", 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);
        }
    }
    
    //派生出新的数组
    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);//1,2
        NSLog(@"array2:%@", array2);//1,2,3
        NSLog(@"array3:%@", array3);//1,2,4,5
        
        NSArray *array4 = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil];
        NSRange range = NSMakeRange(1, 2);
        NSArray *array5 = [array4 subarrayWithRange:range];
        NSLog(@"array5:%@", array5);//2,3
    }
    
    #pragma mark 数组的其他用法
    void arrayOther() {
        NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil];
        // 1-2-3-4
        // 利用分隔符-拼接所有的数组元素
        NSString *str = [array componentsJoinedByString:@"-"];
        NSLog(@"%@", str);
        // 将一个数组写入文件(生成的是一个xml文件)
        NSString *path = @"/Users/user/Desktop/array.xml";
        [array writeToFile:path atomically:YES];
        // 从文件中读取数组内容(文件有严格的格式要求)
        path = @"/Users/user/Desktop/array.xml";
        NSArray *array2 = [NSArray arrayWithContentsOfFile:path];
        NSLog(@"array2:%@", array2);
    }
    
    //数组排序1
    void arraySort1() {
        NSArray *array = [NSArray arrayWithObjects:@"2", @"3", @"1", @"4", 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);
    }
    
    //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];
        // 指定排序的比较方法
        NSArray *array2 = [array sortedArrayUsingSelector:@selector(compareStudent:)];
        NSLog(@"array2:%@", array2);
    }
    
    //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];
        // 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);
    }
    
    //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];
        // 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];
        NSArray *array2 = [array sortedArrayUsingDescriptors:descs];
        NSLog(@"array2:%@", array2);
    }
    
    int main(int argc, const char * argv[])
    {
    
        @autoreleasepool {
            arraySort4();
        }
        return 0;
    }
    
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  • 原文地址:https://www.cnblogs.com/hezhuangzhuang/p/5116794.html
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