Bridging Header Method Parameter Issue
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I'm trying to learn how to use Bridging Headers in this test project. For this part, I want to have a method where it takes in and returns a CGPoint array.
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import <CoreGraphics/CoreGraphics.h>
@interface OpenCVWrapper : NSObject
+ (UIImage *)grayscaleImage:(UIImage *)image;
+ (UIImage *)gaussianBlurImage:(UIImage *)image;
+ (UIImage *)cannyEdgeImage:(UIImage *)image;
//Error says Expected a type
+ ([CGPoint *])lineEdges:([CGPoint *])points;
@end
Because I'm new to this, I don't know where to even start looking for a problem.
objective-c swift bridging-header
asked Nov 11 at 2:41
Richard Sun
82
add a comment |
up vote
1
down vote
favorite
I'm trying to learn how to use Bridging Headers in this test project. For this part, I want to have a method where it takes in and returns a CGPoint array.
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import <CoreGraphics/CoreGraphics.h>
@interface OpenCVWrapper : NSObject
+ (UIImage *)grayscaleImage:(UIImage *)image;
+ (UIImage *)gaussianBlurImage:(UIImage *)image;
+ (UIImage *)cannyEdgeImage:(UIImage *)image;
//Error says Expected a type
+ ([CGPoint *])lineEdges:([CGPoint *])points;
@end
Because I'm new to this, I don't know where to even start looking for a problem.
objective-c swift bridging-header
asked Nov 11 at 2:41
Richard Sun
82
Bridging header is not something you write manually. How is yourOpenCVWrapperis defined? Swift class or Objective-C class?
– OOPer
Nov 11 at 2:52
Sorry, I'm not sure I understand your question (I'm still new to this). I think that OpenCVWrapper is an Objective-C interface. I'm using the OpenCV framework, which I believe is in c++.
– Richard Sun
Nov 12 at 1:43
You write Objective-C interface in combination with Objective-C implementation. The interface is needed to write the implementation, not for the bridging header. Or else when you write a Swift class, Xcode generates a bridging header. Have you written thatOpenCVWrapperis an Objective-C class in the text of your question?
– OOPer
Nov 12 at 11:50
Yes, I understand what you mean. OpenCVWrapper is an Objective-C class
– Richard Sun
Nov 13 at 21:22
add a comment |
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I'm trying to learn how to use Bridging Headers in this test project. For this part, I want to have a method where it takes in and returns a CGPoint array.
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import <CoreGraphics/CoreGraphics.h>
@interface OpenCVWrapper : NSObject
+ (UIImage *)grayscaleImage:(UIImage *)image;
+ (UIImage *)gaussianBlurImage:(UIImage *)image;
+ (UIImage *)cannyEdgeImage:(UIImage *)image;
//Error says Expected a type
+ ([CGPoint *])lineEdges:([CGPoint *])points;
@end
Because I'm new to this, I don't know where to even start looking for a problem.
objective-c swift bridging-header
asked Nov 11 at 2:41
Richard Sun
82
I'm trying to learn how to use Bridging Headers in this test project. For this part, I want to have a method where it takes in and returns a CGPoint array.
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import <CoreGraphics/CoreGraphics.h>
@interface OpenCVWrapper : NSObject
+ (UIImage *)grayscaleImage:(UIImage *)image;
+ (UIImage *)gaussianBlurImage:(UIImage *)image;
+ (UIImage *)cannyEdgeImage:(UIImage *)image;
//Error says Expected a type
+ ([CGPoint *])lineEdges:([CGPoint *])points;
@end
Because I'm new to this, I don't know where to even start looking for a problem.
objective-c swift bridging-header
objective-c swift bridging-header
asked Nov 11 at 2:41
Richard Sun
82
asked Nov 11 at 2:41
Richard Sun
82
asked Nov 11 at 2:41
Richard Sun
82
asked Nov 11 at 2:41
Richard Sun
82
asked Nov 11 at 2:41
Richard Sun
82
82
Bridging header is not something you write manually. How is yourOpenCVWrapperis defined? Swift class or Objective-C class?
– OOPer
Nov 11 at 2:52
Sorry, I'm not sure I understand your question (I'm still new to this). I think that OpenCVWrapper is an Objective-C interface. I'm using the OpenCV framework, which I believe is in c++.
– Richard Sun
Nov 12 at 1:43
You write Objective-C interface in combination with Objective-C implementation. The interface is needed to write the implementation, not for the bridging header. Or else when you write a Swift class, Xcode generates a bridging header. Have you written thatOpenCVWrapperis an Objective-C class in the text of your question?
– OOPer
Nov 12 at 11:50
Yes, I understand what you mean. OpenCVWrapper is an Objective-C class
– Richard Sun
Nov 13 at 21:22
add a comment |
Bridging header is not something you write manually. How is yourOpenCVWrapperis defined? Swift class or Objective-C class?
– OOPer
Nov 11 at 2:52
Sorry, I'm not sure I understand your question (I'm still new to this). I think that OpenCVWrapper is an Objective-C interface. I'm using the OpenCV framework, which I believe is in c++.
– Richard Sun
Nov 12 at 1:43
You write Objective-C interface in combination with Objective-C implementation. The interface is needed to write the implementation, not for the bridging header. Or else when you write a Swift class, Xcode generates a bridging header. Have you written thatOpenCVWrapperis an Objective-C class in the text of your question?
– OOPer
Nov 12 at 11:50
Yes, I understand what you mean. OpenCVWrapper is an Objective-C class
– Richard Sun
Nov 13 at 21:22
Bridging header is not something you write manually. How is your
OpenCVWrapper is defined? Swift class or Objective-C class?– OOPer
Nov 11 at 2:52
Bridging header is not something you write manually. How is your
OpenCVWrapper is defined? Swift class or Objective-C class?– OOPer
Nov 11 at 2:52
Sorry, I'm not sure I understand your question (I'm still new to this). I think that OpenCVWrapper is an Objective-C interface. I'm using the OpenCV framework, which I believe is in c++.
– Richard Sun
Nov 12 at 1:43
Sorry, I'm not sure I understand your question (I'm still new to this). I think that OpenCVWrapper is an Objective-C interface. I'm using the OpenCV framework, which I believe is in c++.
– Richard Sun
Nov 12 at 1:43
You write Objective-C interface in combination with Objective-C implementation. The interface is needed to write the implementation, not for the bridging header. Or else when you write a Swift class, Xcode generates a bridging header. Have you written that
OpenCVWrapper is an Objective-C class in the text of your question?– OOPer
Nov 12 at 11:50
You write Objective-C interface in combination with Objective-C implementation. The interface is needed to write the implementation, not for the bridging header. Or else when you write a Swift class, Xcode generates a bridging header. Have you written that
OpenCVWrapper is an Objective-C class in the text of your question?– OOPer
Nov 12 at 11:50
Yes, I understand what you mean. OpenCVWrapper is an Objective-C class
– Richard Sun
Nov 13 at 21:22
Yes, I understand what you mean. OpenCVWrapper is an Objective-C class
– Richard Sun
Nov 13 at 21:22
add a comment |
1 Answer
1
active
oldest
votes
up vote
0
down vote
accepted
Since you need to return an array of CGPoint, your array should hold a NSValue type, because the array cannot hold struct type
+ (NSArray<NSValue *> *)lineEdges:(NSArray<NSValue *> *)points;
and you should call your method as
NSArray *lineEdges = [OpenCVWrapper lineEdges:@[[NSValue valueWithCGPoint:CGPointMake(3.3, 4.4)]]];
The return value also should be in NSValue and extracting
NSValue *val = [lineEdges objectAtIndex:0];
CGPoint p = [val CGPointValue];
answered Nov 11 at 18:32
cool_jb
345
Thank you, this works perfectly. Also, I've been seeing the asterisk symbol a lot in some sample code. I've read that its a pointer, whose value is actually a reference to a location. Is this correct?
– Richard Sun
Nov 12 at 1:48
Yes thats correct. For more details on pointers you can go through this stackoverflow.com/questions/897366/…. Also please mark the answer as accepted, so that it may help others identify the right working solution
– cool_jb
Nov 12 at 4:38
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
0
down vote
accepted
Since you need to return an array of CGPoint, your array should hold a NSValue type, because the array cannot hold struct type
+ (NSArray<NSValue *> *)lineEdges:(NSArray<NSValue *> *)points;
and you should call your method as
NSArray *lineEdges = [OpenCVWrapper lineEdges:@[[NSValue valueWithCGPoint:CGPointMake(3.3, 4.4)]]];
The return value also should be in NSValue and extracting
NSValue *val = [lineEdges objectAtIndex:0];
CGPoint p = [val CGPointValue];
answered Nov 11 at 18:32
cool_jb
345
Thank you, this works perfectly. Also, I've been seeing the asterisk symbol a lot in some sample code. I've read that its a pointer, whose value is actually a reference to a location. Is this correct?
– Richard Sun
Nov 12 at 1:48
Yes thats correct. For more details on pointers you can go through this stackoverflow.com/questions/897366/…. Also please mark the answer as accepted, so that it may help others identify the right working solution
– cool_jb
Nov 12 at 4:38
add a comment |
up vote
0
down vote
accepted
Since you need to return an array of CGPoint, your array should hold a NSValue type, because the array cannot hold struct type
+ (NSArray<NSValue *> *)lineEdges:(NSArray<NSValue *> *)points;
and you should call your method as
NSArray *lineEdges = [OpenCVWrapper lineEdges:@[[NSValue valueWithCGPoint:CGPointMake(3.3, 4.4)]]];
The return value also should be in NSValue and extracting
NSValue *val = [lineEdges objectAtIndex:0];
CGPoint p = [val CGPointValue];
answered Nov 11 at 18:32
cool_jb
345
Thank you, this works perfectly. Also, I've been seeing the asterisk symbol a lot in some sample code. I've read that its a pointer, whose value is actually a reference to a location. Is this correct?
– Richard Sun
Nov 12 at 1:48
Yes thats correct. For more details on pointers you can go through this stackoverflow.com/questions/897366/…. Also please mark the answer as accepted, so that it may help others identify the right working solution
– cool_jb
Nov 12 at 4:38
add a comment |
up vote
0
down vote
accepted
up vote
0
down vote
accepted
Since you need to return an array of CGPoint, your array should hold a NSValue type, because the array cannot hold struct type
+ (NSArray<NSValue *> *)lineEdges:(NSArray<NSValue *> *)points;
and you should call your method as
NSArray *lineEdges = [OpenCVWrapper lineEdges:@[[NSValue valueWithCGPoint:CGPointMake(3.3, 4.4)]]];
The return value also should be in NSValue and extracting
NSValue *val = [lineEdges objectAtIndex:0];
CGPoint p = [val CGPointValue];
answered Nov 11 at 18:32
cool_jb
345
Since you need to return an array of CGPoint, your array should hold a NSValue type, because the array cannot hold struct type
+ (NSArray<NSValue *> *)lineEdges:(NSArray<NSValue *> *)points;
and you should call your method as
NSArray *lineEdges = [OpenCVWrapper lineEdges:@[[NSValue valueWithCGPoint:CGPointMake(3.3, 4.4)]]];
The return value also should be in NSValue and extracting
NSValue *val = [lineEdges objectAtIndex:0];
CGPoint p = [val CGPointValue];
answered Nov 11 at 18:32
cool_jb
345
answered Nov 11 at 18:32
cool_jb
345
answered Nov 11 at 18:32
cool_jb
345
answered Nov 11 at 18:32
cool_jb
345
345
Thank you, this works perfectly. Also, I've been seeing the asterisk symbol a lot in some sample code. I've read that its a pointer, whose value is actually a reference to a location. Is this correct?
– Richard Sun
Nov 12 at 1:48
Yes thats correct. For more details on pointers you can go through this stackoverflow.com/questions/897366/…. Also please mark the answer as accepted, so that it may help others identify the right working solution
– cool_jb
Nov 12 at 4:38
add a comment |
Thank you, this works perfectly. Also, I've been seeing the asterisk symbol a lot in some sample code. I've read that its a pointer, whose value is actually a reference to a location. Is this correct?
– Richard Sun
Nov 12 at 1:48
Yes thats correct. For more details on pointers you can go through this stackoverflow.com/questions/897366/…. Also please mark the answer as accepted, so that it may help others identify the right working solution
– cool_jb
Nov 12 at 4:38
Thank you, this works perfectly. Also, I've been seeing the asterisk symbol a lot in some sample code. I've read that its a pointer, whose value is actually a reference to a location. Is this correct?
– Richard Sun
Nov 12 at 1:48
Thank you, this works perfectly. Also, I've been seeing the asterisk symbol a lot in some sample code. I've read that its a pointer, whose value is actually a reference to a location. Is this correct?
– Richard Sun
Nov 12 at 1:48
Yes thats correct. For more details on pointers you can go through this stackoverflow.com/questions/897366/…. Also please mark the answer as accepted, so that it may help others identify the right working solution
– cool_jb
Nov 12 at 4:38
Yes thats correct. For more details on pointers you can go through this stackoverflow.com/questions/897366/…. Also please mark the answer as accepted, so that it may help others identify the right working solution
– cool_jb
Nov 12 at 4:38
add a comment |
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Bridging header is not something you write manually. How is your
OpenCVWrapperis defined? Swift class or Objective-C class?– OOPer
Nov 11 at 2:52
Sorry, I'm not sure I understand your question (I'm still new to this). I think that OpenCVWrapper is an Objective-C interface. I'm using the OpenCV framework, which I believe is in c++.
– Richard Sun
Nov 12 at 1:43
You write Objective-C interface in combination with Objective-C implementation. The interface is needed to write the implementation, not for the bridging header. Or else when you write a Swift class, Xcode generates a bridging header. Have you written that
OpenCVWrapperis an Objective-C class in the text of your question?– OOPer
Nov 12 at 11:50
Yes, I understand what you mean. OpenCVWrapper is an Objective-C class
– Richard Sun
Nov 13 at 21:22