（转）Object－C字符串使用总结

字符串常用方法

int main (int argc, const char * argv[])
{
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    // 字符串的创建和初始化
    NSString* sFormat = [[NSString alloc] initWithFormat:@"Year:%d", 2009];
    NSString* sString = [[NSString alloc] initWithString:sFormat];
    NSString* sTmp = nil;
    // 获取长度
    NSUInteger uLen = [sFormat length];
    NSLog(@"uLen = %u", uLen);
    // 获取指定索引处的字符
    NSUInteger index = 0;
    unichar c = [sFormat characterAtIndex:index];
    NSLog(@"The character at index %u of \"%@\" is \'%c\'", index, sFormat, c);
    // 字符串大小写转换
    /*
     Case transformations aren’t guaranteed to be symmetrical or to
     produce
     strings of the same lengths as the originals. The result of this
     statement:
     lcString = [myString lowercaseString];
     might not be equal to this statement:
     lcString = [[myString uppercaseString] lowercaseString];
     For example, the uppercase form of “ß” in German is “SS”, so
     converting
     “Straße” to uppercase, then lowercase, produces this sequence of
     strings:
     “Straße”
     “STRASSE”
     “strasse”
     */  
    sTmp = [sFormat lowercaseString];
    NSLog(@"Lowercase String of %@ is %@", sFormat, sTmp);
    sTmp = [sString uppercaseString];
    NSLog(@"Uppercase String of %@ is %@", sString, sTmp);
    // 字符串比较 
    // 地址比较 
    if (@"Year:2009" == sFormat) {
        NSLog(@"The address of sFormat is equal to constant string \"Year:2009\"");
    }
    else
    {
        NSLog(@"The address of sFormat isn't equal to constant string \"Year:2009\"");
    }
    // 内容比较