fix: add type-safety for screenshots result array (#4843)

The screenshots array had wrong typing causing crashes due to type casting.

Author: philprime

CHANGELOG.md

@@ -21,6 +21,7 @@
 
 - Fix missing `sample_rate` in baggage (#4751)
 - Serializing SentryGeo with `nil` values (#4724)
+- Add type-safety for screenshots result array (#4843)
 
 ### Internal
 

Sources/Sentry/SentryScreenshot.m

@@ -21,9 +21,9 @@ - (instancetype)init
     return self;
 }
 
-- (NSArray<NSData *> *)appScreenshotsFromMainThread
+- (NSArray<UIImage *> *)appScreenshotsFromMainThread
 {
-    __block NSArray *result;
+    __block NSArray<UIImage *> *result;
 
     void (^takeScreenShot)(void) = ^{ result = [self appScreenshots]; };
 
@@ -33,6 +33,18 @@ - (instancetype)init
     return result;
 }
 
+- (NSArray<NSData *> *)appScreenshotDatasFromMainThread
+{
+    __block NSArray<NSData *> *result;
+
+    void (^takeScreenShot)(void) = ^{ result = [self appScreenshotsData]; };
+
+    [[SentryDependencyContainer sharedInstance].dispatchQueueWrapper
+        dispatchSyncOnMainQueue:takeScreenShot];
+
+    return result;
+}
+
 - (void)saveScreenShots:(NSString *)imagesDirectoryPath
 {
     // This function does not dispatch the screenshot to the main thread.

Sources/Sentry/SentryScreenshotIntegration.m

@@ -85,8 +85,8 @@ - (void)uninstall
         return attachments;
     }
 
-    NSArray *screenshot =
-        [SentryDependencyContainer.sharedInstance.screenshot appScreenshotsFromMainThread];
+    NSArray<NSData *> *screenshot =
+        [SentryDependencyContainer.sharedInstance.screenshot appScreenshotDatasFromMainThread];
 
     NSMutableArray *result =
         [NSMutableArray arrayWithCapacity:attachments.count + screenshot.count];

Sources/Sentry/include/SentryScreenshot.h

@@ -12,7 +12,13 @@ NS_ASSUME_NONNULL_BEGIN
  * Get a screenshot of every open window in the app.
  * @return An array of @c NSData instances containing PNG images.
  */
-- (NSArray<NSData *> *)appScreenshotsFromMainThread;
+- (NSArray<NSData *> *)appScreenshotDatasFromMainThread;
+
+/**
+ * Get a screenshot of every open window in the app.
+ * @return An array of @c UIImage instances.
+ */
+- (NSArray<UIImage *> *)appScreenshotsFromMainThread;
 
 /**
  * Save the current app screen shots in the given directory.

Tests/SentryTests/Integrations/Screenshot/TestSentryScreenShot.swift

@@ -3,15 +3,16 @@
 class TestSentryScreenshot: SentryScreenshot {
 
     var result: [Data] = []
+    var images: [UIImage] = []
     var processScreenshotsCallback: (() -> Void)?
 
     override func appScreenshotsData() -> [Data] {
         processScreenshotsCallback?()
         return result
     }
 
-    override func appScreenshotsFromMainThread() -> [Data] {
-        return result
+    override func appScreenshotsFromMainThread() -> [UIImage] {
+        return images
     }
 }
 

Tests/SentryTests/SentryScreenShotTests.swift

@@ -26,6 +26,7 @@ class SentryScreenShotTests: XCTestCase {
     }
 
     func test_IsMainThread() {
+        // -- Arrange --
         let testWindow = TestWindow(frame: CGRect(x: 0, y: 0, width: 10, height: 10))
         var isMainThread = false
 
@@ -35,15 +36,16 @@ class SentryScreenShotTests: XCTestCase {
 
         fixture.uiApplication.windows = [testWindow]
 
-        let queue = DispatchQueue(label: "TestQueue")
-        
+        // -- Act --
         let expect = expectation(description: "Screenshot")
+        let queue = DispatchQueue(label: "TestQueue")
         let _ = queue.async {
             self.fixture.sut.appScreenshotsFromMainThread()
             expect.fulfill()
         }
-                
         wait(for: [expect], timeout: 1)
+
+        // -- Assert --
         XCTAssertTrue(isMainThread)
     }