• ObjectiveC 的Foundation库总结


    Foundation库提供了基本的数据结构,包括strings, arrays, dictionaries等。

    NSString

     
    —–创建字符串的方法—–
    //1、创建常量字符串
        NSString *astring = @”This is a String!”;
    //2、先创建一个空的字符串,然后赋值;
    //    alloc和init组合则适合在函数之间传递参数,用完之后需要手工release
        NSString *astring = [[NSString alloc] init];
    astring = @”This is a String!”;
    //3、在以上方法中,提升速度:initWithString方法
        NSString *astring = [[NSString allocinitWithString:@”This is a String!”];
    //4、创建临时字符串
        NSString *astring;
    astring = [NSString stringWithCString:"This is a temporary string"];
    // OR
        NSString *  scriptString = [NSString stringWithString:@" tell application \"Mail\"\r"];
    //5、创建格式化字符串:占位符(由一个%加一个字符组成)
        int i = 1;
    int j = 2;
    NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%d.This is %i string!",i,j]];

    —–从文件读取字符串—–
    NSString *path = @”astring.text”;
    NSString *astring = [[NSString alloc] initWithContentsOfFile:path];

    —–写字符串到文件—-
    NSString *astring = [[NSString alloc] initWithString:@”This is a String!”];
    NSString *path = @”astring.text”;
    [astring writeToFile: path atomically: YES];
    —–比较两个字符串—–
    //1、用C比较:strcmp函数
    char string1[] = “string!”;
    char string2[] = “string!”;
    if(strcmp(string1, string2) = = 0)
    {
    NSLog(@”1″);
    }
    //2、isEqualToString方法
    NSString *astring01 = @”This is a String!”;
    NSString *astring02 = @”This is a String!”;
    BOOL result = [astring01 isEqualToString:astring02];
    //3、compare方法(comparer返回的三种值:NSOrderedSame,NSOrderedAscending,NSOrderedDescending)
    NSString *astring01 = @”This is a String!”;
    NSString *astring02 = @”This is a String!”;
    BOOL result = [astring01 compare:astring02] = = NSOrderedSame;   //NSOrderedSame 判断两者内容是否相同

    NSString *astring01 = @”This is a String!”;
    NSString *astring02 = @”this is a String!”;
    BOOL result = [astring01 compare:astring02] = = NSOrderedAscending;
    NSLog(@”result:%d”,result);
    //NSOrderedAscending 判断两对象值的大小(按字母顺序进行比较,astring02大于astring01为真)

    NSString *astring01 = @”this is a String!”;
    NSString *astring02 = @”This is a String!”;
    BOOL result = [astring01 compare:astring02] = = NSOrderedDescending;
    NSLog(@”result:%d”,result);
    //NSOrderedDescending 判断两对象值的大小(按字母顺序进行比较,astring02小于astring01为真)
    //4、不考虑大小写比较字符串1
    NSString *astring01 = @”this is a String!”;
    NSString *astring02 = @”This is a String!”;
    BOOL result = [astring01 caseInsensitiveCompare:astring02] = = NSOrderedSame;
    NSLog(@”result:%d”,result);
    //NSOrderedDescending判断两对象值的大小(按字母顺序进行比较,astring02小于astring01为真)
    //5、不考虑大小写比较字符串2
    NSString *astring01 = @”this is a String!”;
    NSString *astring02 = @”This is a String!”;
    BOOL result = [astring01 compare:astring02
    options:NSCaseInsensitiveSearch | NSNumericSearch] = = NSOrderedSame;
    NSLog(@”result:%d”,result);
    //NSCaseInsensitiveSearch:不区分大小写比较 NSLiteralSearch:进行完全比较,区分大小写 NSNumericSearch:比较字符串的字符个数,而不是字符值。

    总结一下字符串比较:可以统一使用下面函数来比较字符串, 对于进行特殊的大小比较,mask确定特殊比较的类型:例如大小写敏感、数字排序还是字符排序等等。具体见枚举类型NSStringCompareOptions的具体值。

    - (NSComparisonResult)compare:(NSString *)string options:(NSStringCompareOptions)mask;

    —–改变字符串的大小写—–
    NSString *string1 = @”A String”;
    NSString *string2 = @”String”;
    NSLog(@”string1:%@”,[string1 uppercaseString]);//uppercaseString返回转换为大写的字符串
    NSLog(@”string2:%@”,[string2 lowercaseString]);//lowercaseString返回转换为小写的字符串
    NSLog(@”string2:%@”,[string2 capitalizedString]);//capitalizedString返回每个单词首字母大写的字符串

    —–在串中搜索子串 —–

    NSString *string1 = @”This is a string”;
    NSString *string2 = @”string”;
    NSRange range = [string1 rangeOfString:string2];
    int location = range.location;
    int leight = range.length;
    NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%i,Leight:%i",location,leight]];
    NSLog(@”astring:%@”,astring);
    [astring release];

    —–抽取子串 —–

    //1、-substringToIndex: 从字符串的开头一直截取到指定的位置,但不包括该位置的字符
    NSString *string1 = @”This is a string”;
    NSString *string2 = [string1 substringToIndex:3];
    NSLog(@”string2:%@”,string2);

    //2、-substringFromIndex: 以指定位置开始(包括指定位置的字符),并包括之后的全部字符
    NSString *string1 = @”This is a string”;
    NSString *string2 = [string1 substringFromIndex:3];
    NSLog(@”string2:%@”,string2);

    //3、-substringWithRange: //按照所给出的位置,长度,任意地从字符串中截取子串
    NSString *string1 = @”This is a string”;
    NSString *string2 = [string1 substringWithRange:NSMakeRange(0, 4)];
    NSLog(@”string2:%@”,string2);

    //4、快速枚举
    for(NSString *filename in direnum)    {
    if([[filename pathExtension] isEqualToString:@”jpg”]){
    [files addObject:filename];
    }
    }
        NSLog(@”files:%@”,files);//5、枚举
    NSEnumerator *filenum;
    filenum = [files objectEnumerator];
    while (filename = [filenum nextObject]) {
    NSLog(@”filename:%@”,filename);
    }

    @”b”,@”a”,@”e”,@”d”,@”c”,@”f”,@”h”,@”g”,nil];
    NSLog(@”oldArray:%@”,oldArray);
    NSEnumerator *enumerator;
    enumerator = [oldArray objectEnumerator];
    id obj;
    while(obj = [enumerator nextObject])    {
    [newArray addObject: obj];
    }
    [newArray sortUsingSelector:@selector(compare:)];
    NSLog(@”newArray:%@”, newArray);
    [newArray release];
    —–切分数组—–
    //1、从字符串分割到数组- componentsSeparatedByString:
    NSString *string = [[NSString alloc] initWithString:@”One,Two,Three,Four”];
    NSLog(@”string:%@”,string);
    NSArray *array = [string componentsSeparatedByString:@","];
    NSLog(@”array:%@”,array);
    [string release];

    //2、从数组合并元素到字符串- componentsJoinedByString:
    NSArray *array = [[NSArray alloc] initWithObjects:@”One”,@”Two”,@”Three”,@”Four”,nil];
    NSString *string = [array componentsJoinedByString:@","];
    NSLog(@”string:%@”,string);

    —–从目录搜索扩展名为jpg的文件—–
    //NSFileManager *fileManager = [NSFileManager defaultManager];
    NSString *home;
    home = @”../Users/”;
    NSDirectoryEnumerator *direnum;
    direnum = [fileManager enumeratorAtPath: home];
    NSMutableArray *files = [[NSMutableArray alloc] init];
    //枚举
    NSString *filename;
    while (filename = [direnum nextObject]) {
    if([[filename pathExtension] hasSuffix:@”jpg”]){
    [files addObject:filename];
    }
    }
    //扩展路径
        NSString *Path = @”~/NSData.txt”;
    NSString *absolutePath = [Path stringByExpandingTildeInPath];
    NSLog(@”absolutePath:%@”,absolutePath);
    NSLog(@”Path:%@”,[absolutePath stringByAbbreviatingWithTildeInPath]);
    //文件扩展名
    NSString *Path = @”~/NSData.txt”;
    NSLog(@”Extension:%@”,[Path pathExtension]);

    —–查找与替换—–

    - (NSString *)stringByReplacingCharactersInRange :( NSRange)range withString:(NSString *)replacement

    - (NSString *)stringByReplacingOccurrencesOfString :( NSString *)target withString:(NSString *)replacement

    NSMutableString(可修改的字符串)
    NSObject -> NSString -> NSMutableString
    Common NSMutableString methods
    + (id)string;
    - (void)appendString:(NSString *)string;
    - (void)appendFormat:(NSString *)format, …;
    —–给字符串分配容量—–
    //stringWithCapacity:
    NSMutableString *String;
    String = [NSMutableString stringWithCapacity:40];
    —–在已有字符串后面添加字符—–//appendString: and appendFormat:
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@”This is a NSMutableString”];
    //[String1 appendString:@", I will be adding some character"];
    [String1 appendFormat:[NSString stringWithFormat:@", I will be adding some character"]];
    NSLog(@”String1:%@”,String1);
    —– 在已有字符串中按照所给出范围删除字符—-
    //deleteCharactersInRange:
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@”This is a NSMutableString”];
    [String1 deleteCharactersInRange:NSMakeRange(0, 5)];    // 删除指定范围(location=0,length=5)的字符串
    NSLog(@”String1:%@”,String1);
    —-在已有字符串后面在所指定的位置中插入给出的字符串—–
    //-insertString: atIndex:
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@”This is a NSMutableString”];
    [String1 insertString:@"Hi! " atIndex:0];
    NSLog(@”String1:%@”,String1);
    [String1 insertString:@"and StringEnd", atIndex:[String1 length]];  //  在可变字符串的最后插入
    —-将已有的空符串换成其它的字符串—–
    //-setString:
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@”This is a NSMutableString”];
    [String1 setString:@"Hello Word!"];
    NSLog(@”String1:%@”,String1);—-查找—–
    NSRange subRange = [String1 rangeOfString:@"is a"];   // 如果没查找到,则 (subRange.location == NSNotFound)为真。—-按照所给出的范围替换的原有的字符—–
    //-setString:
    NSMutableString *String1 = [[NSMutableString alloc] initWithString:@”This is a NSMutableString”];
    [String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];     // 用于NSMutableString
    NSLog(@”String1:%@”,String1);—-在给定的范围查找替换—–
    - (NSUInteger)replaceOccurrencesOfString :( NSString *)target withString :( NSString *)replacement options :( NSStringCompareOptions)opts range :( NSRange)searchRange
    —-判断字符串内是否还包含别的字符串(前缀,后缀)—–
    //01: 检查字符串是否以另一个字符串开头- (BOOL) hasPrefix: (NSString *) aString;
    NSString *String1 = @”NSStringInformation.txt”;
    [String1 hasPrefix:@"NSString"] = = 1 ?  NSLog(@”YES”) : NSLog(@”NO”);
    [String1 hasSuffix:@".txt"] = = 1 ?  NSLog(@”YES”) : NSLog(@”NO”);//02: 查找字符串某处是否包含给定的字符串 – (NSRange) rangeOfString: (NSString *) aString,这一点前面在串中搜索子串用到过

    NSRange subRange;
    subRange = [string1 rangeOfString:@"string A"];  //查找字符串string1中是否包含“string A”。返回NSRange类型。
    if(subRange.location == NSNotFound)
    NSLog(@”String not found “);
    else  NSLog(@”string is at index %lu, length is %lu”, subRange.location, subRange.length);

    Arrays 

    创建一个Array:

    NSArray* myArray = @[@"one", @"two", @"three"];

    获取数组中的元素:

    NSString* oneString = myArray[0];
    NSString* twoString = myArray[1];

    ios5以前:

    NSString* oneString = [myArray objectAtIndex:0];

    得到元素的索引:

    NSArray* myArray = @[@"one", @"two", @"three"];
    int index = [myArray indexOfObject:@"two"]; // should be equal to 1

    if (index == NSNotFound) {
    NSLog(@”Couldn’t find the object!”);

    }

    从数组中得到子数组:

      NSArray* myArray = @[@"one", @"two", @"three"];
        NSRange subArrayRange = NSMakeRange(1,2);
        NSArray* subArray = [myArray subArrayWithRange:subArrayRange];

    遍历数组:

    NSArray* myArray = @[@"one", @"two", @"three"];

    for (NSString* string in myArray) {
    // this code is repeated 3 times, one for each item in the array

    }

    Mutable Arrays :

    NSMutableArray* myArray = [NSMutableArray arrayWithArray:@[@"One", @"Two"]]; // Add “Three” to the end

    [myArray addObject:@"Three"]; // Add “Zero” to the start

    [myArray insertObject:@"Zero" atIndex:0];
    // The array now contains “Zero”, “One”, “Two”, “Three”.

     NSMutableArray* myArray = [NSMutableArray arrayWithArray:
                @[@"One", @"Two", @"Three"]];

    [myArray removeObject:@"One"]; // removes “One”
    [myArray removeObjectAtIndex:1]; // removes “Three”, the second

    NSMutableArray* myArray = [NSMutableArray arrayWithArray:@[@"One", @"Two",
                                                                   @"Three"]];

    [myArray replaceObjectAtIndex:1 withObject:@"Bananas"];

    Dictionaries 

    creating NSDictionary :

      NSDictionary* translationDictionary = @{
            @"greeting": @"Hello",
            @"farewell": @"Goodbye"
    
    };

    从NSDictionary中取值:

     NSDictionary* translationDictionary = @{@"greeting": @"Hello"};
        NSString* greeting = translationDictionary[@"greeting"];

    遍历:

    for (NSString* key in aDictionary) {

    NSObject* theValue = aDictionary[key]; // do something with theValue

    }

    mutable dictionary :

    NSMutableDictionary* aDictionary = @{};
        aDictionary[@"greeting"] = @"Hello";
        aDictionary[@"farewell"] = @"Goodbye";

    NSValue and NSNumber

    Container classes such as NSArray and NSDictionary can only contain Objective-C

    objects.

    To create an NSNumber from a number, simply put an @ in front of it. The compiler will

    work out what kind of number it is (double, float, character, boolean, and so on) and

    create an NSNumber for you:

    NSNumber* theNumber = @123;

    int myValue = [theNumber intValue];

    The NSData class is designed to be a container for arbitrary data. It contains bytes, and

    doesn’t make any assumptions about what kind of bytes they are

    NSString* filePath = @”/Examples/Test.txt”;

    NSData* loadedData = [NSData dataWithContentsOfFile:filePath];

    NSString* filePath = @”/Examples/Test.txt”;

    [loadedData writeToFile:filePath atomically:YES];

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  • 原文地址:https://www.cnblogs.com/shangdahao/p/2964262.html
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