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 alloc] initWithString:@”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);—-在给定的范围内查找并替换—–
- (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];