iOS-类型转换

NSString 转 NSData

• NSString -> NSData

NSString *string;
NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];

• NSData -> NSString

NSData *data;
NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

NSString 转 NSURL

• NSString -> NSURL

NSString *string;
NSURL *url = [NSURL URLWithString:string];

• NSURL -> NSString

NSURL *url;
NSString *string = [url absoluteString];

NSString 转 NSNumber

• NSString -> NSNumber

NSString *string;
NSNumber *num = @([string integerValue]);

• NSNumber -> NSString

NSNumber *num;
NSString *string = [num stringValue];

NSString 转 Char *

• NSString -> Char *

NSString *string;
const char *c = [string cStringUsingEncoding:NSUTF8StringEncoding];

• Char * -> NSString

const char *c;
NSString *string = [NSString stringWithUTF8String:c];
// or
NSString *string = [NSString stringWithCString:c encoding:NSUTF8StringEncoding];

NSString 转 NSInterger

• NSString -> NSInterger

NSString *string;
NSInteger i = [string integerValue];

• NSInterger -> NSString

NSInteger i;
NSString *string = [@(i) stringValue];
// or
NSString *string = [NSString stringWithFormat:@"%ld", i];

NSData 转 UIImage

• NSData -> UIImage

UIImage *image;
NSData *data = UIImagePNGRepresentation(image);
// or
NSData *data = UIImageJPEGRepresentation(image, 1);

• UIImage -> NSData

NSData *data;
UIImage *image = [[UIImage alloc] initWithData:data];

NSData 转 NSDictionary

• NSData -> NSDictionary

NSData *data;
NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];

• NSDictionary -> NSData

NSDictionary *dict;
NSData *data = [NSJSONSerialization dataWithJSONObject:dict options:NSJSONWritingPrettyPrinted error:nil];

NSData 转 NSArray

• NSData -> NSArray

NSData *data;
NSArray *arr = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];

• NSArray -> NSData

NSArray *arr;
NSData *data = [NSJSONSerialization dataWithJSONObject:arr options:NSJSONWritingPrettyPrinted error:nil];

暂时想到的就这些，之后会继续补充~