IOS Foundation 字符串实例分析

作者：朱克锋

邮箱：zhukefeng@iboxpay.com

转载请注明出处：http://blog.youkuaiyun.com/linux_zkf

1，基本字符串操作

- (void) basicStringManipulation

{

// 创建字符串

NSString *myString =@"A string constant";

myString = [NSString stringWithFormat:@"The number is %d", 5]; 

// 追加字符串

NSLog(@"%@", [myStringstringByAppendingString:@"22"]);

NSLog(@"%@", [myStringstringByAppendingFormat:@"%d",22]);

// 字符串长度和位置字符

NSLog(@"%d", myString.length);

printf("%c\n", [myStringcharacterAtIndex:2]);

// 把NSString字符串转化为C字符串

printf("%s\n", [myStringUTF8String]);

printf("%s\n", [myStringcStringUsingEncoding: NSUTF8StringEncoding]);

// 把C字符串转化为NSString

NSLog(@"%@", [NSStringstringWithCString:"Hello World"encoding: NSUTF8StringEncoding]);

}

2，字符串字串操作

- (void) showcaseSubstrings

{

//把字符串转化为数组

NSString *myString =@"One Two Three Four Five Six Seven";

NSArray *wordArray = [myStringcomponentsSeparatedByString:@" "];

NSLog(@"%@", wordArray);

//截取字串

NSString *sub1 = [myString substringToIndex:7];

NSLog(@"%@", sub1);

NSString *sub2 = [myString substringFromIndex:4];

NSLog(@"%@", sub2);

//使用NSRange操作子串

NSRange r;

r.location = 4;

r.length = 2;

NSString *sub3 = [myString substringWithRange:r];

NSLog(@"%@", sub3);

NSRange searchRange = [myStringrangeOfString:@"Five"];

if (searchRange.location !=NSNotFound)

{

NSLog(@"Range location: %d, length: %d", searchRange.location, searchRange.length);

NSLog(@"%@", [myStringstringByReplacingCharactersInRange:searchRange withString:@"New String"]);

}

//字符串替代

NSString *replaced = [myStringstringByReplacingOccurrencesOfString:@" "withString:@" * "];

NSLog(@"%@", replaced);

}

3,字符串大小写转换

- (void) caseChanges

{

NSString *myString =@"Hello world. How do you do?";

//大写

NSLog(@"%@", [myStringuppercaseString]);

//小写

NSLog(@"%@", [myStringlowercaseString]);

//首字母大写

NSLog(@"%@", [myStringcapitalizedString]);

}

4,字符串比较

- (void) compareAndTest

{

NSString *s1 =@"Hello World";

NSString *s2 =@"Hello Mom";

//是否相同

NSLog(@"%@ %@ %@", s1, [s1isEqualToString:s2] ? @"equals" :@"differs from", s2);

//是否以某字符串开头

NSLog(@"%@ %@ %@", s1, [s1hasPrefix:@"Hello"] ?@"starts with" : @"does not start with",@"Hello");

//是否以某字符串结尾

NSLog(@"%@ %@ %@", s1, [s1hasSuffix:@"Hello"] ?@"ends with" : @"does not end with",@"Hello");

}

5,字符串转换为数字

- (void) convertToNumbers

{

NSString *s1 =@"3.141592";

//int类型

NSLog(@"%d", [s1intValue]);

//bool类型

NSLog(@"%d", [s1boolValue]);

//float类型

NSLog(@"%f", [s1floatValue]);

//double类型

NSLog(@"%f", [s1doubleValue]);

}

6,可变字符串

- (void) mutableStrings;

{

NSMutableString *myString = [NSMutableStringstringWithString:@"Hello World. "];

[myString appendFormat:@"The results are %@ now.",@"in"];

NSLog(@"%@", myString);

}