Add OFString (QString)

ObjQt.pro

@@ -10,6 +10,7 @@ INCLUDEPATH += common	\
 	       QtWidgets
 
 HEADERS += common/helpers.h		\
+	   common/OFString+QString.h	\
 	   common/QtOwnershipManaging.h	\
 	   QtCore/QtChildEvent.h	\
 	   QtCore/QtCoreApplication.h	\
@@ -21,7 +22,8 @@ HEADERS += common/helpers.h		\
 	   QtWidgets/QtApplication.h	\
 	   QtWidgets/QtWidget.h
 
-SOURCES += QtCore/QtChildEvent.mm	\
+SOURCES += common/OFString+QString.mm	\
+	   QtCore/QtChildEvent.mm	\
            QtCore/QtCoreApplication.mm	\
 	   QtCore/QtEvent.mm  		\
 	   QtCore/QtObject.mm		\

common/OFString+QString.h

@@ -0,0 +1,9 @@
+#import <ObjFW/ObjFW.h>
+
+#include <QString>
+
+@interface OFString (QString)
++ (instancetype)stringWithQString: (const QString&)qString;
+- initWithQString: (const QString&)qString;
+- (QString)qString;
+@end

common/OFString+QString.mm

@@ -0,0 +1,30 @@
+#import "OFString+QString.h"
+
+@implementation OFString (QString)
++ stringWithQString: (const QString&)qString
+{
+	return [[[self alloc] initWithQString: qString] autorelease];
+}
+
+- initWithQString: (const QString&)qString
+{
+	static_assert(sizeof(QChar) == sizeof(of_char16_t),
+	    "QChar and of_char16_t have a different size!");
+
+	return [self initWithUTF16String: (of_char16_t*)qString.data()
+				  length: qString.length()];
+}
+
+- (QString)qString
+{
+	static_assert(sizeof(of_char16_t) == sizeof(QChar),
+	    "of_char16_t and QChar have a different size!");
+
+	void *pool = objc_autoreleasePoolPush();
+	QString ret = QString((QChar*)[self UTF16String]);
+
+	objc_autoreleasePoolPop(pool);
+
+	return ret;
+}
+@end

common/helpers.h

@@ -4,16 +4,18 @@
 #include <QSize>
 #include <QRect>
 
+#import "OFString+QString.h"
+
 static OF_INLINE OFString*
 toOF(const QString &qString)
 {
-	return [OFString stringWithUTF8String: qString.toUtf8()];
+	return [OFString stringWithQString: qString];
 }
 
 static OF_INLINE QString
 toQt(OFString *string)
 {
-	return QString::fromUtf8([string UTF8String]);
+	return [string qString];
 }
 
 static OF_INLINE of_point_t