NSString *str;

// 使用stringWithFormat生成一格式化字符串

str = [NSString stringWithFormat:@"This is %@","John"];

NSLog(@"str--->%@",str);

// 字符串长度length;

NSLog(@"The length of this string is %@",[str length]);

// 字符串比较 isEqualToString, 返回NO(false)，isEqualToString区分大小写

BOOL isequal = [str isEqualToString:@"this is John"];

// 字符串序列比列 compare,返回结果NSComparisonResult

// type enum _NSComparisonResult{

// NSOrderedAscending = -1,

// NSOrderedSame,

// NSOrderedDescending

// }

int result = [@"bool" compare:@"cool"];

NSLog(@"The result is %d",result);

// compare 比较规则options

// NSLiteralSearch 区分大小写(完全比较)

// NSCaseInsensitiveSearch 不区分大小写

// NSNumericSearch 只比较字符串的个数，而不比较字符串的字面值

int result1 = [@"This is John" compare:@"this is John" options:NSCaseInsensitiveSearch | NSNumericSearch];

NSLog(@"The result is %d",result1);

// 字符串开头是否包括另一字符串 hasPrefix,返回结果YES(true)

BOOL isHas = [str hasPrefix:@"This"];

// 字符串结尾是否包括另一字符串 hasSuffix,返回结果YES(true)

BOOL isHas = [str hasSuffix:@"John"];

// 查找字符串在另一字符串中的位置

NSRange range = [str rangeOfString:@"is" options:NSCaseInsensitiveSearch];

NSLog(@"The location in the string named 'str' of 'is' is @d",range.location);