Foundation库提供了基本的数据结构,包括strings, arrays, dictionaries等。
NSString
astring = @”This is a String!”;
//4、创建临时字符串
astring = [NSString stringWithCString:"This is a temporary string"];
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
+ (id)string;
- (void)appendString:(NSString *)string;
- (void)appendFormat:(NSString *)format, …;
//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];