C24_OC14-NSString字符串

1.NSString和文件操作

#import <Foundation/Foundation.h>
int main()
{
    NSString * str1 = @"字符串定义";
    NSString * str2 = [NSString stringWithFormat:@"%d", 100];
    NSString * str3 = [[NSString alloc] initWithString:@"string"];
    NSString * str4 = [[NSString alloc] initWithFormat:@"%d", 200];
    NSString * str5 = [NSString stringWithUTF8String:"24rjsl;dkjg"];
    char * strC = [str5 UTF8String];
    NSString * str6 = [[NSString alloc]
                       initWithContentsOfFile:@"/Users/vigiles/Desktop/1.txt"
                       encoding:NSUTF8StringEncoding error:nil];
    NSString * str7 = [NSString
                       stringWithContentsOfURL:[NSURL URLWithString:@"file:///Users/vigiles/Desktop/1.txt"]
                       encoding:NSUTF8StringEncoding error:nil];
    
    [@"写入文件\n换行\n制表\t制表"
     writeToFile:@"/Users/vigiles/Desktop/2.txt"    // 重复文件会覆盖原有内容
     atomically:YES
     encoding:NSUTF8StringEncoding
     error:nil];
    [@"写入文件\n换行\n制表\t制表"
     writeToURL:[NSURL fileURLWithPath:@"/Users/vigiles/Desktop/3.txt"]
     atomically:YES
     encoding:NSUTF8StringEncoding
     error:nil];
}

2.NSMutableString

#import <Foundation/Foundation.h>
int main()
{
    NSMutableString * str1 = [NSMutableString new];
    NSMutableString * str2 = [NSMutableString stringWithFormat:@"%d", 100];
    NSMutableString * str3 = [[NSMutableString alloc] initWithString:@"string"];
    NSMutableString * str4 = [[NSMutableString alloc] initWithFormat:@"%d", 200];
    NSMutableString * str5 = [NSMutableString stringWithUTF8String:"24rjsl;dkjg"];
    char * strC = [str5 UTF8String];
    NSMutableString * str6 = [[NSMutableString alloc]
                       initWithContentsOfFile:@"/Users/vigiles/Desktop/1.txt"
                       encoding:NSUTF8StringEncoding error:nil];
    NSMutableString * str7 = [NSMutableString
                       stringWithContentsOfURL:[NSURL URLWithString:@"file:///Users/vigiles/Desktop/1.txt"]
                       encoding:NSUTF8StringEncoding error:nil];
    
    /** 这个是stringByAppendingString的返回值 **/
    NSString * ns = [@"原NSString" stringByAppendingString:@"追加内容"];
    NSLog(@"%@", ns);
    
    /** 追加字串。这个没有返回值，因为是可变数组 **/
    [str1 appendString:@"追加的字符串"];
    NSLog(@"%@", str1);
    
    // 获取子字串的区间位置
    NSRange srange = [str1 rangeOfString:@"追加的"];
    
    /** 删除字串。这个没有返回值，因为是可变数组 **/
    [str1 deleteCharactersInRange:srange];
    NSLog(@"%@", str1);
}