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 程序猿神奇的手，每时每刻，这双手都在改变着世界的交互方式！ 本文转自当天真遇到现实博客园博客，原文链接：http://www.cnblogs.com/XYQ-208910/p/4740101.html，如需转载请自行联系原作者
)
