Objective-C：NSArray的常见操作
NSArray不可变字符串的主要操作有：创建、枚举、排序、与NSString之间的相互转换
注意：
NSArray可以存对象，不可以存基本数据类型、结构体、数组、指针、nil、NULL
NSArray用nil作为结束标识符。
NSNull可以代表一个空对象。
整个操作还是通过代码来体现吧：
.h Person类的声明文件如下：
#import <Foundation/Foundation.h>
@interface Person : NSObject
@property(nonatomic,copy)NSString* name;
@property(nonatomic,assign)NSInteger age;
+(Person*)personWithName:(NSString*)name andAge:(NSInteger)age;
-(id)initWithName:(NSString*)name andAge:(NSInteger)age;
-(NSComparisonResult)compareByName:(Person *)aPerson;//声明排序方式为通过姓名比较
-(NSComparisonResult)compareByAge:(Person *)aPerson;//声明排序方式为通过年龄比较
@end
.m Person类的实现文件如下：
#import "Person.h"
@implementation Person
+(Person*)personWithName:(NSString*)name andAge:(NSInteger)age
{
return [[Person alloc]initWithName:name andAge:age];
}
-(id)initWithName:(NSString*)name andAge:(NSInteger)age
{
self = [super init];
if(self)
{
_name = name;
_age = age;
}
return self;
}
-(NSString*)description//由于数组存储的是自定义的对象Person对象,所以复写description方法，将NSlog重新格式化输出
{
return [NSString stringWithFormat:@"name=%@,age=%ld",_name,_age];
}
-(NSComparisonResult)compareByName:(Person *)aPerson //返回一个selector选择器选择的比较方式,字符串比较默认为NSOrderAsecding
{
return [_name compare:aPerson.name];
}
-(NSComparisonResult)compareByAge:(Person *)aPerson//与上同理
{
if(_age > aPerson.age)
return NSOrderedDescending;
else if (_age < aPerson.age)
return NSOrderedAscending;
else
return NSOrderedSame;
}
@end
主函数测试如下：
#import <Foundation/Foundation.h>
#import "Person.h"
int main(int argc, const char * argv[])
{
@autoreleasepool
{
//NSArray测试
/*
NSArray可以存对象，不可以存基本数据类型、结构体、数组、指针、nil、NULL
NSArray用nil作为结束标识符。
NSNull可以代表一个空对象。
*/
//创建一个空对象
NSNull *nul = [NSNull null];
//在一个array中不要求只存相同类型的对象，可以存储任意类型的对象
NSArray *arr = @[@1,@"one",@"2",nul];
NSLog(@"%@",arr);
//枚举
NSEnumerator *enumerator = [arr objectEnumerator];
id obj;
while(obj = [enumerator nextObject])
{
NSLog(@"%@",obj);
}
//保存到文件中(必须是OC内置的对象,自定义的对象会出错)
[arr writeToFile:@"/Users/mac/Desktop/arr.txt" atomically:YES];
//读文件创建NSArray
NSArray *arr1 = [NSArray arrayWithContentsOfFile:@"/Users/mac/Desktop/arr.txt"];
NSLog(@"%@",arr1);
//排序
NSArray *arr2 = @[@2,@5,@1,@4,@3];
NSArray *sorted = [arr2 sortedArrayUsingSelector:@selector(compare:)];
NSLog(@"%@",sorted);
NSArray *arr3 = @[@"two",@"three",@"five",@"one",@"four"];
NSArray *sorted2 = [arr3 sortedArrayUsingSelector:@selector(compare:)];
NSLog(@"%@",sorted2);
//自定义对象的排序
NSArray *arrayperson = @[[Person personWithName:@"Tom" andAge:25],
[Person personWithName:@"Jobs" andAge:23],
[Person personWithName:@"Bill" andAge:26],
[Person personWithName:@"John" andAge:21]];
//按姓名排序
NSArray *sortedByName = [arrayperson sortedArrayUsingSelector:@selector(compareByName:)];
NSLog(@"%@",sortedByName);
//按年龄排序
NSArray *sortedByAge = [arrayperson sortedArrayUsingSelector:@selector(compareByAge:)];
NSLog(@"%@",sortedByAge);
//NSArray和NSString
NSString *str = @"this is a test";
NSArray *words = [str componentsSeparatedByString:@" "];//分隔符
NSLog(@"%@",words);
NSString *str2 = [words componentsJoinedByString:@"-"]; //连接符
NSLog(@"%@",str2);
}
return 0;
}
测试结果如下所示：
2015-08-18 17:37:39.772 01-NSArray[1948:112551] ( 1, one, 2, "<null>" ) 2015-08-18 17:37:39.795 01-NSArray[1948:112551] 1 2015-08-18 17:37:39.796 01-NSArray[1948:112551] one 2015-08-18 17:37:39.797 01-NSArray[1948:112551] 2 2015-08-18 17:37:39.797 01-NSArray[1948:112551] <null> 2015-08-18 17:37:39.798 01-NSArray[1948:112551] (null) 2015-08-18 17:37:39.798 01-NSArray[1948:112551] ( 1, 2, 3, 4, 5 ) 2015-08-18 17:37:39.799 01-NSArray[1948:112551] ( five, four, one, three, two ) 2015-08-18 17:37:39.799 01-NSArray[1948:112551] ( "name=Bill,age=26", "name=Jobs,age=23", "name=John,age=21", "name=Tom,age=25" ) 2015-08-18 17:37:39.800 01-NSArray[1948:112551] ( "name=John,age=21", "name=Jobs,age=23", "name=Tom,age=25", "name=Bill,age=26" ) 2015-08-18 17:37:39.800 01-NSArray[1948:112551] ( this, is, a, test ) 2015-08-18 17:37:39.800 01-NSArray[1948:112551] this-is-a-test Program ended with exit code: 0
