Foundation中各种初始化创建

来源：互联网发布：天天动听mac 编辑：程序博客网时间：2024/05/01 00:00

NSString

初始化字符串一

//经典字符串初始化        NSString *q1=@"      暗号";//这样初始化,系统自动帮我们管理释放内存        NSLog(@"%@",q1);

初始化字符串二

//(重点)格式化字符串        NSString *a=@"虎",*b=@"妖";        NSString *q2=[NSString stringWithFormat:@"天网盖地%@,宝塔镇河%@",a,b];        NSLog(@"%@",q2);

初始化字符串三

NSString *q3=[[NSString alloc]init];//需要自己来释放内存        q3=@"    芝麻开门";        NSLog(@"%@",q3);

NSSMutableString

//初始化一

NSMutableString *str1=[[NSMutableString alloc]initWithCapacity:10];        //实例化的另一种方法  写一个分配字符串的大小,不可以超过这个范围        [str1 setString:@"Hello"];//因为为可变,所以要这样赋值初始化,        NSLog(@"%@",str1);

//初始化二

NSMutableString *str2=[[NSMutableString alloc]init];        [str2 appendFormat:@"Hello"];        NSLog(@"%@",str2);

NSString *c=@" world";        [str2 appendFormat:@"%@",c];        NSLog(@"%@",str2);

NSArray

//初始化一

NSArray *array1=[[NSArray alloc]initWithObjects:@"1",@"2",@"3",@"4",@"5", nil];//因为是不可变的数组,实例化时必须对它赋值  nil(niu)为结束.        NSLog(@"%@",array1);

//初始化二

SArray *array2 = @[@"abc",@"def"];        NSLog(@"%@",array2);

//初始化三:通过c数组初始化NSArray

NSString *str3[3];        str3[0] = @"11";        str3[1] = @"22";        str3[2] = @"33";        NSArray *array3 = [NSArray arrayWithObjects:str3 count:3];        NSLog(@"%@",array3);

NSMutableArray

//初始化一

NSMutableArray *array4 = [[NSMutableArray alloc] initWithObjects:@"1",@"2",@"3", nil];        NSLog(@"%@",array4);

//初始化二

(先写一个类,初始化定义)

Ps.h

#import <Foundation/Foundation.h>@interface Ps : NSObject@property(nonatomic,strong)NSString *Name;- (instancetype)initWithName:(NSString *)Name;@end

Ps.m

#import "Ps.h"@implementation Ps- (instancetype)initWithName:(NSString *)Name//初始化{    self = [super init];    if (self) {        _Name=Name;    }    return self;}- (NSString *)description//输出显示{    return [NSString stringWithFormat:@"%@", _Name];}@end

开始初始化

Ps *p1=[[Ps alloc]initWithName:@"zs"];        Ps *p2=[[Ps alloc]initWithName:@"ls"];        Ps *p3=[[Ps alloc]initWithName:@"ww"];                NSMutableArray *array5=[[NSMutableArray alloc]initWithObjects:p1,p2,p3, nil];        NSLog(@"%@",array5);

//初始化三

NSMutableArray *array6=[[NSMutableArray alloc]init];        [array6 addObject:p1];//添加单个元素        NSLog(@"%@",array6);        [array6 addObjectsFromArray:array5];//从数组中所有元素添加        NSLog(@"%@",array6);

NSDictionary(key value键值对的形式存储(三种创建方法))

//初始化一

NSDictionary *dic1=[NSDictionary dictionaryWithObject:@"1" forKey:@"a"];        NSLog(@"%@",dic1);

//初始化二(可以添加多组键值对)

NSDictionary *dic2 = [[NSDictionary alloc] initWithObjectsAndKeys:@"1",@"a",@"2",@"b", nil];        NSLog(@"%@",dic2);                NSDictionary *dic3=[NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@"1",@"2",@"3", nil] forKeys:[NSArray arrayWithObjects:@"a",@"b",@"c", nil]];        NSLog(@"dict2=%@",dic3);

//初始化三:新版本简便写法

NSDictionary *dic4=@{@"a":@"1",@"b":@"2"};//前面为key,和前面相反        NSLog(@"%@",dic4);

NSMutableDictionary

//初始化一

NSMutableDictionary *dic5=[[NSMutableDictionary alloc]init];        [dic5 setObject:@"1" forKey:@"a"];        [dic5 setObject:@"2" forKey:@"b"];        NSLog(@"%@",dic5)

//初始化二

NSMutableDictionary *dic6= [NSMutableDictionary dictionaryWithObject:@"value3" forKey:@"key3"];        NSLog(@"%@",dic6);

//初始化三

NSMutableDictionary *dic7= [[NSMutableDictionary alloc] initWithObjectsAndKeys:@"value",@"key",@"value2",@"key2", nil];        NSLog(@"%@",dic7);

0 0