Object C 几种常见类型之间的相互转换

1.NSURL 与 NSString

　　1)NSURL 转 NSString:

NSString * urlStr = [url absoluteString];

　　2)NSString 转 NSURL:

NSURL * url = [NSURL URLWithString:urlStr];
NSURL * url = [[NSURL alloc] initWithString:urlStr];

 

2.NSString 与 char

　　1)NSString 转 char

NSString *_urlStr = @"www";
const char *url = [_urlStr cStringUsingEncoding:NSUTF8StringEncoding];

　　2)char 转NSString:

char *url = "www";
NSString *_url = [[NSString alloc]initWithCstring:url encoding:NSUTF8StringEncoding];
//Another method
NSString *_url = [NSString stringWithCstring:(const char*)url encoding:NSUTF8StringEncoding];

3.NSString 与 int

　　1)NSString 转 int

NSString *_urlStr = @"123";
int uid = [_urlStr intValue];

 4.NSString与bytes

NSString *test=@"ABCDEFGHIJKLMNOPQRSTUVWXYZ";
NSUInteger bytes = [test lengthOfBytesUsingEncoding:NSUTF8StringEncoding];
NSLog(@"%i bytes", bytes)