I searched on google and on SO but didn't find any useful help for this issue.
I'm trying to translate this code from objective-c to swift:
- (void)metaTitleUpdated:(NSString *)title {
NSLog(#"delegate title updated to %#", title);
NSArray *chunks = [title componentsSeparatedByString:#";"];
if ([chunks count]) {
NSArray *streamTitle = [[chunks objectAtIndex:0] componentsSeparatedByString:#"="];
if ([streamTitle count] > 1) {
titleLabel.text = [streamTitle objectAtIndex:1];
}
}
}
so far i have translated it to this:
func metaTitleUpdated(input: String) {
println("delegate title updated to \(title)")
let chunks: NSArray = title!.componentsSeparatedByString(";")
if (chunks.count) {
let streamTitle = chunks .objectAtIndex(0) .componentsSeparatedByString(";")
if (streamTitle.count > 1) {
titleLabel.text = streamTitle.objectAtIndex(1)
}
}
}
but i always get the error "Type 'Int' does not conform to protocol 'BooleanType'" in the line: if (chunks.count) {
What does cause this error? Is the rest of the code in swift correct or are there any other errors?
chunks.count has the type Int, but the if statement requires a boolean expression.
This is different from (Objective-)C, where the controlling expression of an if statement can have any scalar type and is compared with zero.
So the corresponding Swift code for
if ([chunks count]) { ... }
is
if chunks.count != 0 { ... }
I solved the answer by myself.
func metaTitleUpdated(title: String) {
var StreamTitle = split(title) {$0 == "="}
var derRichtigeTitel: String = StreamTitle[1]
titleLabel.text = derRichtigeTitel
println("delegate title updated to \(derRichtigeTitel)")
}
Related
I have an example in Swift language:
guard let windowScene = view.window?.windowScene else { return }
windowScene.requestGeometryUpdate(.iOS(interfaceOrientations: .portrait)) { error in }
I can't write it in Objective C:
UIWindowScene *windowScene = self.view.window.windowScene;
[windowScene requestGeometryUpdateWithPreferences: UIInterfaceOrientationMaskPortrait errorHandler:nil];
Please tell me how to write correctly I will be grateful for any help.
One way to write that Swift code in Objective-C would be:
UIWindowScene *windowScene = self.view.window.windowScene;
if (!windowScene) { return; }
UIWindowSceneGeometryPreferences *preferences = [[UIWindowSceneGeometryPreferencesIOS alloc] initWithInterfaceOrientations:UIInterfaceOrientationMaskPortrait];
[windowScene requestGeometryUpdateWithPreferences:preferences errorHandler:^(NSError * _Nonnull error) {
// Handle error here
}];
I'm having trouble porting this Objective-C code to Swift. The code must sort the contents of a directory by a given property.
NSArray *contents = [fileManager contentsOfDirectoryAtURL:directoryURL includingPropertiesForKeys:#[property] options:kNilOptions error:&error];
if (!contents) return nil;
contents = [contents sortedArrayUsingComparator:^NSComparisonResult(NSURL *url1, NSURL *url2) {
id value1;
if ([url1 getResourceValue:&value1 forKey:property error:nil]) return NSOrderedAscending;
id value2;
if ([url2 getResourceValue:&value2 forKey:property error:nil]) return NSOrderedDescending;
return [value1 compare:value2];
}];
return contents
My Swift version so far:
if let contents = fileManager.contentsOfDirectoryAtURL(directoryURL, includingPropertiesForKeys: [property], options: NSDirectoryEnumerationOptions.allZeros, error: &error) as? [NSURL] {
let sortedContents = contents.sorted({(URL1 : NSURL, URL2 : NSURL) -> Bool in
var value1 : AnyObject?
if !URL1.getResourceValue(&value1, forKey: property, error: nil) { return true }
var value2 : AnyObject?
if !URL2.getResourceValue(&value2, forKey: property, error: nil) { return false }
// How do I compare AnyObject?
return false
})
return sortedContents
} else {
return nil
}
Particularly, I don't know how to compare two AnyObject objects. I can't downcast to the Comparable protocol because it's not marked as #objc and apparently I can't call compare with optional chaining syntax (error: Operand of postfix '?' should have optional type; type is 'NSComparisonResult').
Of course, there's always the brute-force approach of downcasting the values to String, NSDate and NSNumber:
if let string1 = value1 as? String {
if let string2 = value2 as? String {
return string1 < string2
}
}
if let date1 = value1 as? NSDate {
if let date2 = value2 as? NSDate {
return date1.compare(date2) == NSComparisonResult.OrderedAscending
}
}
// And so on...
return false
Is there a better way?
Unless they really are AnyObject (ie., they can be swift things) declare them (or cast them) to NSObject instead.
The problem is not with the receiver type of AnyObject (that is fine; you can call any known objc method with AnyObject); but with the parameter type. There is no single signature of compare:. There's one that takes NSString; one that takes NSNumber; one that takes NSDate, etc., but none that is general, none that takes AnyObject.
I am starting to learn Swift and hope to find it an excellent replacement for Objective C.
I am attempting to convert my Objective C classes into Swift and I cannot find the best way to translate the following method into Swift.
#implementation VersionReader
- (NSString *)readVersionFromString:(NSString *)string {
if (string.length == 0) {
return nil;
}
unichar firstChar = [string characterAtIndex:0];
if (firstChar < '0' || firstChar > '9') {
return nil;
}
NSUInteger length = string.length;
for (NSUInteger i = 0; i < length; ++i) {
if ([string characterAtIndex:i] == ' ') {
return [string substringToIndex:i];
}
}
return string;
}
#end
So far my Swift code looks like this:
import Cocoa
class VersionReader {
func readVersionFromString(string: String) -> String? {
if (string.isEmpty) {
return nil
}
var firstChar = string.characterAtIndex[0]
if (firstChar < 48 || firstChar > 57) {
return nil
}
var length = string.utf16Count
for (var i = 0; i < length; ++i) {
if (string.characterAtIndex(i) == 32) {
return string.substringToIndex(i)
}
}
return string
}
}
Tom this, I get the same error on two lines:
'String' does not have a member named 'characterAtIndex'
What would be an alternative to make this work in Swift? Thanks in advance.
A possible Swift solution:
func readVersionFromString(string: String) -> String? {
if string.isEmpty {
return nil
}
let firstChar = string[string.startIndex]
if !find("0123456789", firstChar) {
return nil
} else if let pos = find(string, " ") {
return string.substringToIndex(pos)
} else {
return string
}
}
Swift's String type doesn't have a characterAtIndex method. You can cast it to an NSString and use it as below:
var firstChar = (string as NSString).characterAtIndex(0)
Or
var firstChar = string.bridgeToObjectiveC().characterAtIndex(0)
Note that the characterAtIndex method returns an unichar, which seems to be what you want. But the correct approach to get a Swift Character would be that suggested by FreeAsInBeer in his answer: Array(string)[0]
Swift doesn't have a characterAtIndex selector. Instead, you need to use Array(string)[0].
I was wondering if it's possible to determine the class or primitive type of an Objects properties. Getting all properties names and values is pretty easy. SO answer
So is there any way to get the properties class type while the property hast no value or nil value?
Example Code
#interface MyObject : NSObject
#property (nonatomic, copy) NSString *aString;
#property (nonatomic, copy) NSDate *aDate;
#property NSInteger aPrimitive;
#end
#implementation MyObject
#synthesize aString;
#synthesize aDate;
#synthesize aPrimitive;
- (void)getTheTypesOfMyProperties {
unsigned int count;
objc_property_t* props = class_copyPropertyList([self class], &count);
for (int i = 0; i < count; i++) {
objc_property_t property = props[i];
// Here I can easy get the name or value
const char * name = property_getName(property);
// But is there any magic function that can tell me the type?
// the property can be nil at this time
Class cls = magicFunction(property);
}
free(props);
}
#end
After searching through Apples Documentation about objc Runtime and according to this SO answer I finally got it working. I just want to share my results.
unsigned int count;
objc_property_t* props = class_copyPropertyList([MyObject class], &count);
for (int i = 0; i < count; i++) {
objc_property_t property = props[i];
const char * name = property_getName(property);
NSString *propertyName = [NSString stringWithCString:name encoding:NSUTF8StringEncoding];
const char * type = property_getAttributes(property);
NSString *attr = [NSString stringWithCString:type encoding:NSUTF8StringEncoding];
NSString * typeString = [NSString stringWithUTF8String:type];
NSArray * attributes = [typeString componentsSeparatedByString:#","];
NSString * typeAttribute = [attributes objectAtIndex:0];
NSString * propertyType = [typeAttribute substringFromIndex:1];
const char * rawPropertyType = [propertyType UTF8String];
if (strcmp(rawPropertyType, #encode(float)) == 0) {
//it's a float
} else if (strcmp(rawPropertyType, #encode(int)) == 0) {
//it's an int
} else if (strcmp(rawPropertyType, #encode(id)) == 0) {
//it's some sort of object
} else {
// According to Apples Documentation you can determine the corresponding encoding values
}
if ([typeAttribute hasPrefix:#"T#"]) {
NSString * typeClassName = [typeAttribute substringWithRange:NSMakeRange(3, [typeAttribute length]-4)]; //turns #"NSDate" into NSDate
Class typeClass = NSClassFromString(typeClassName);
if (typeClass != nil) {
// Here is the corresponding class even for nil values
}
}
}
free(props);
Inspired by the ObjC answer by #arndt-bieberstein I have written a solution in Swift 3 (probably very similar - if not same - in earlier versions of Swift). You can find it on Github I am trying to make a pod of it but I am having issues getting pob lib lintto work with the Swift 3 code (CLI xcodebuild or Xcode 8 related problem probably.) Anyhow, the class method func getTypesOfProperties(inClass clazz: NSObject.Type) -> Dictionary<String, Any>? can extract the name and types of any Swift class that inherits from NSObject.
The work horse of the project are these methods, but checkout the full code on Github:
func getTypesOfProperties(in clazz: NSObject.Type) -> Dictionary<String, Any>? {
var count = UInt32()
guard let properties = class_copyPropertyList(clazz, &count) else { return nil }
var types: Dictionary<String, Any> = [:]
for i in 0..<Int(count) {
guard let property: objc_property_t = properties[i], let name = getNameOf(property: property) else { continue }
let type = getTypeOf(property: property)
types[name] = type
}
free(properties)
return types
}
func getTypeOf(property: objc_property_t) -> Any {
guard let attributesAsNSString: NSString = NSString(utf8String: property_getAttributes(property)) else { return Any.self }
let attributes = attributesAsNSString as String
let slices = attributes.components(separatedBy: "\"")
guard slices.count > 1 else { return getPrimitiveDataType(withAttributes: attributes) }
let objectClassName = slices[1]
let objectClass = NSClassFromString(objectClassName) as! NSObject.Type
return objectClass
}
func getPrimitiveDataType(withAttributes attributes: String) -> Any {
guard let letter = attributes.substring(from: 1, to: 2), let type = primitiveDataTypes[letter] else { return Any.self }
return type
}
func getNameOf(property: objc_property_t) -> String? {
guard let name: NSString = NSString(utf8String: property_getName(property)) else { return nil }
return name as String
}
It can extract the NSObject.Type of all properties which class type inherits from NSObject such as NSDate (Swift3: Date), NSString(Swift3: String?) and NSNumber, however it is store in the type Any (as you can see as the type of the value of the Dictionary returned by the method). This is due to the limitations of value types such as Int, Int32, Bool. Since those types do not inherit from NSObject, calling .self on e.g. an Int - Int.self does not return NSObject.Type, but rather the type Any. Thus the method returns Dictionary<String, Any>? and not Dictionary<String, NSObject.Type>?.
You can use this method like this:
class Book: NSObject {
let title: String
let author: String?
let numberOfPages: Int
let released: Date
let isPocket: Bool
init(title: String, author: String?, numberOfPages: Int, released: Date, isPocket: Bool) {
self.title = title
self.author = author
self.numberOfPages = numberOfPages
self.released = released
self.isPocket = isPocket
}
}
guard let types = getTypesOfProperties(inClass: Book.self) else { return }
for (name, type) in types {
print("'\(name)' has type '\(type)'")
}
// Prints:
// 'title' has type 'NSString'
// 'numberOfPages' has type 'Int'
// 'author' has type 'NSString'
// 'released' has type 'NSDate'
// 'isPocket' has type 'Bool'
You can also try to cast the Any to NSObject.Type, which will succeed for all properties inheriting from NSObject, then you can check the type using standard == operator:
func checkPropertiesOfBook() {
guard let types = getTypesOfProperties(inClass: Book.self) else { return }
for (name, type) in types {
if let objectType = type as? NSObject.Type {
if objectType == NSDate.self {
print("Property named '\(name)' has type 'NSDate'")
} else if objectType == NSString.self {
print("Property named '\(name)' has type 'NSString'")
}
}
}
}
If you declare this custom == operator:
func ==(rhs: Any, lhs: Any) -> Bool {
let rhsType: String = "\(rhs)"
let lhsType: String = "\(lhs)"
let same = rhsType == lhsType
return same
}
You can then even check the type of value types like this:
func checkPropertiesOfBook() {
guard let types = getTypesOfProperties(inClass: Book.self) else { return }
for (name, type) in types {
if type == Int.self {
print("Property named '\(name)' has type 'Int'")
} else if type == Bool.self {
print("Property named '\(name)' has type 'Bool'")
}
}
}
LIMITATIONS
I have not yet been able to give this project support for when the value types are optionals. If you have declared a property in you NSObject subclass like this: var myOptionalInt: Int? my solution will not work, because the method class_copyPropertyList can't find those properties.
Does anyone have a solution for this?
We have some code today that takes an NSArray and passes it as a argument list to -[NSString initWithFormat:arguments] and we're trying to get this to work with ARC. Here's the code were using
NSString* format = #"Item %s and Item %s"; // Retrieved elsewhere
NSArray* args = [NSArray arrayWithObjects:#"1", #"2", nil]; // Retrieved elsewhere
// http://cocoawithlove.com/2009/05/variable-argument-lists-in-cocoa.html
char* argsList = (char*) malloc(sizeof(NSString*) * args.count);
[args getObjects:(id*) argsList];
NSString* message = [[[NSString alloc] initWithFormat:format arguments:argsList] autorelease];
free(argsList);
Any recommendations on how to make this ARC compliant? Or we're even open to a better way of doing it.
This only works for arrays with a single element
The answer by chrisco was working well, until I went to compile with 64-bit architecture. This caused an error:
EXC_BAD_ADDRESS type EXC_I386_GPFLT
The solution was to use a slightly different approach for passing the argument list to the method:
+ (id)stringWithFormat:(NSString *)format array:(NSArray*) arguments;
{
__unsafe_unretained id * argList = (__unsafe_unretained id *) calloc(1UL, sizeof(id) * arguments.count);
for (NSInteger i = 0; i < arguments.count; i++) {
argList[i] = arguments[i];
}
NSString* result = [[NSString alloc] initWithFormat:format, *argList] ;// arguments:(void *) argList];
free (argList);
return result;
}
Cannot find a way to do this obj-c but a swift helper class finally got this working (my whole project is obj-c except this class)
#objc class StringFormat: NSObject {
class func format(key: String, args: [AnyObject]) -> String {
let locArgs: [CVarArgType] = args.map({ (arg: AnyObject) -> CVarArgType in
if let iArg = (arg is NSNumber ? arg.intValue : nil) {
return iArg
}
return arg as! CVarArgType
});
return String(format: key, arguments: locArgs)
}
}
There is some magic going on, to do with how [CVarArgType] doesn't behave like a normal array - but this works in the flexible cross architecture way you expect it to.
Expanding on #mcfedr's answer, this Swift 3 helper does the job:
import Foundation
#objc (FTStringFormat) public class StringFormat: NSObject {
#objc public class func format(key: String, args: [AnyObject]) -> String {
let locArgs: [CVarArg] = args.flatMap({ (arg: AnyObject) -> CVarArg? in
if let arg = arg as? NSNumber {
return arg.intValue
}
if let arg = arg as? CustomStringConvertible {
return arg.description
}
return nil
});
return String(format: key, arguments: locArgs)
}
}
Calling from Objective-C:
[FTStringFormat formatWithKey:#"name: %# age: %d" args:#[#"John", #(42)]]
For the %# format specifier we're using Swift's CustomStringConvertible protocol in order to call description on all of the array members.
Supporting all number format specifiers like %d and %f is not really possible because the NSNumber object doesn't reveal if it's an integer or float. So we could only support one or the other. Here we use intValue, so %d is supported but %f and %g are not.
The only thing you need to do is remove the autorelease.
You're malloc'ing and free'ing yourself - ARC doesn't care about that.
I write solution use NSInvocation and signatures.
Answer create in this.
Also I write detailed description how it work but only on Russian ((
Maybe it help for someone.
I tried mcfedr's code. Somehow, my Xcode 11 treated CVarArgType as undeclared type, so I investigated into this for a while.
I didn't not understand the closure part of his/her code. And, I just simplified to hard casted each element to CVarArg using as! operator.
func format(key: String, args: [Any]) -> String {
return String(format: key, arguments: args.map { ($0 as! CVarArg) })
}
let doubleValue: Double = 1.25
let floatValue: Float = 2.75
let intValue: Int = 3
let numberValue: NSNumber = 4.5 as NSNumber
let hello: String = "Hello"
let world: NSString = "World" as NSString
print(format(key: "double: %f, float: %f, int: %d, number: %#, %#, %#", args: [doubleValue, floatValue, intValue, numberValue, hello, world]))
// double: 1.250000, float: 2.750000, int: 3, number: 4.5, Hello, World
It seems it's working fine under swift 5.1, but there may be some pitfalls.