Idimport <Foundation/Foundation.h>
/**
NSString中常用的类方法
+ (nullable instancetype)stringWithUTF8String:(const char *)nullTerminatedCString;
instancetypetype 作为返回值 代表返回的是当前这个类的对象
作用：将C语言的字符串转化为OC字符串对象
+ (instancetype)stringWithFormat:(NSString *)format, ... NS_FORMAT_FUNCTION(1,2);
作用：拼接一个字符串对象
NSString中常用的对象方法
1). length 方法 返回值 NSUInteger ,得到字符串的字符的个数，可以处理中文
2). characterAtIndex 得到字符串中指定下标的字符
- (unichar)characterAtIndex:(NSUInteger)index;
3). 判断两个字符串是否相等
- (BOOL)isEqualToString:(NSString *)aString;
4). 比较字符串大小
- (NSComparisonResult)compare:(NSString *)string;
NSComparisonResult :
typedef NS_CLOSED_ENUM(NSInteger, NSComparisonResult) {
NSOrderedAscending = -1L,
NSOrderedSame,
NSOrderedDescending
};
*/
int main(int argc, const char * argv[]) {
@autoreleasepool {
NSString *str = @"qwertyuiop";
NSUInteger len = [str length];
NSLog(@"%ld", len);
unichar ch = [str characterAtIndex:2];
NSLog(@"ch = %C", ch);
NSString *str1 = @"qq";
NSString *str2 = [NSString stringWithFormat:@"qq"];
BOOL b = [str1 isEqualToString:str2];
NSLog(@"%d", b);
NSComparisonResult res = [str1 compare:str2];
NSLog(@"%ld", res);
}
return 0;
}
转载链接：https://my.oschina.net/wwyywg/blog/4497019
剑龙御武 
![[爱了]](/js/img/d1.gif)
![[尴尬]](/js/img/d16.gif)