ios nsstring(补充 与不同类型之间的转化）

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转载：http://www.cnblogs.com/superhappy/archive/2012/01/31/2332938.html

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参照《iphone SDK 3开发快速上手》编写，特此声明

//创建一个NSString

NSString *myString1 = @"some string";

NSLog(@"%@",myString1);



//格式化创建

NSString *myString2 = [NSString stringWithFormat:@"%@",myString1];

NSLog(@"%@",myString2);

//返回数字的值

NSString *myString3 = @"1234abc";

double doubleString = [myString3 floatValue];//获得123

NSLog(@"%f",doubleString);

int intString = [myString3 intValue];//获得123

NSLog(@"%d",intString);

NSUInteger stringLenth = [myString3 length];

/*NSUinteger 的输出方式为%lu*/

NSLog(@"%lu",stringLenth);

//比较两个字符串,若相同返回TURE

BOOL areEqual =

[myString1 isEqualToString:myString2];

NSLog(@"areEqual = %d",areEqual);

//区分大小写的比较

BOOL areEqual1 = ([myString1 caseInsensitiveCompare:myString2] == NSOrderedSame);

NSLog(@"areEqual1 = %d",areEqual1);

//转换大小写

NSString *myString4 = @"asdfg";

NSString *upper = [myString4 uppercaseString];

NSString *lower = [upper lowercaseString];

NSLog(@"upper = %@",upper);

NSLog(@"lower = %@",lower);



//截去字符串(以空格为例)

NSString *myString5 = @" one two three ";

NSString *trimmed1 = [myString5 stringByTrimmingCharactersInSet:[NSCharacterSetwhitespaceAndNewlineCharacterSet]];

//whitespaceAndNewlineCharacterSet去除前后的空格和换行符

NSString *trimmed2 = [myString5 stringByTrimmingCharactersInSet:[NSCharacterSetwhitespaceCharacterSet]];

//whitespaceCharacterSet 去除前后的空格,实际效果来看只实现了去除首字母前面的空格

NSLog(@"myString5 = %@",myString5);

NSLog(@"trimmed1 = %@",trimmed1);

NSLog(@"trimmed2 = %@",trimmed2);

//predicate 断言断定，使基于,下面的方法实现删除空格

NSPredicate *noE = [NSPredicatepredicateWithFormat:@"SELF!=''"];

NSArray *part = [myString5 componentsSeparatedByCharactersInSet:[NSCharacterSetwhitespaceCharacterSet]];

NSArray *file = [part filteredArrayUsingPredicate:noE];

NSString *trimmed3 = [file componentsJoinedByString:@""];

NSLog(@"trimmed3 = %@",trimmed3);



//有已知字符串创建子字符串

NSString * number = @"abx cdefghi gklmn";

//substringToIndex获取字符串的前三个

//substringFromIndex从第三个开始截取到最后

NSString *myString6 = [number substringToIndex:3];

NSLog(@"myString6 = %@",myString6);



NSRange range = NSMakeRange(4, 5);

//用边界截取起始位置为第四个，长度为5个长度

NSString *aString = [number substringWithRange:range];

NSLog(@"aString = %@",aString);

//创建成数组

NSArray *arr = [number componentsSeparatedByString:@" "];

NSLog(@"arr = %@",arr);

//替换子字符串

NSString *myString7 = [number stringByReplacingOccurrencesOfString:@"efg"withString:@"aaa"];

NSLog(@"myString7 = %@",myString7);

//查找子字符串,这段代码返回（4,3）;

NSRange found = [number rangeOfString:@"cde"];

NSLog(@"found.location = %lu",found.location);

NSLog(@"%lu",found.length);

//判读那是否包含

BOOL found1 = ([number rangeOfString:@"cde"].location !=NSNotFound);

NSLog(@"found1 = %lu",found1);

//组合字符串

NSString *myString9 = [myString1 stringByAppendingString:myString7];

NSLog(@"myString9 = %@,myString1 = %@,myString7 = %@",myString9,myString1,myString7);



NSString *myString10 = [myString1 stringByAppendingFormat:myString7];

NSLog(@"myString10 = %@,myString1 = %@,myString7 = %@",myString10,myString1,myString7);



//将文件内容写入到字符串中

NSString *fileContents = [NSString stringWithContentsOfFile:@"123.text"];

//获取文件扩展名

NSString *filename = @"11111.txt";

NSString *fileExtension = [filename pathExtension];

NSLog(@"fileExtension = %@",fileExtension);



//将URL内容写入字符串,有点问题

NSURL *url = [NSURLURLWithString:@"http://www.baidu.com"];

NSLog(@"url = %@",url);

NSString *pageContents = [NSString stringWithContentsOfURL:url];

//NSLog(@"pageContents = %@",pageContents);

//-------------------------------------------------------------------------------------------------------------//

原文地址：NSString与int和float的相互转换作者：leisurehuang34

NSString *tempA = @"123";

NSString *tempB = @"456";

1，字符串拼接

NSString *newString = [NSString stringWithFormat:@"%@%@",tempA,tempB];

2，字符转int

int intString = [newString intValue];

3，int转字符

NSString *stringInt = [NSString stringWithFormat:@"%d",intString];

4，字符转float

float floatString = [newString floatValue];

5，float转字符

NSString *stringFloat = [NSString stringWithFormat:@"%f",intString];