feat(apple): Add custom performance metrics (#5629)

Co-authored-by: lizokm <lizka920@gmail.com>

src/platform-includes/performance/automatic-performance-metrics/android.mdx

@@ -1,4 +1,4 @@
 If configured, the Android SDK automatically collects the following performance metrics:
 
-* Cold and warm app start time - learn more in <PlatformLink to="/performance/instrumentation/automatic-instrumentation/#app-start-instrumentation">App Start Instrumentation</PlatformLink>.
-* Frozen and slow frame rendering - learn more in <PlatformLink to="/performance/instrumentation/automatic-instrumentation/#slow-and-frozen-frames">Slow and Frozen Frames</PlatformLink>.
+* <PlatformLink to="/performance/instrumentation/automatic-instrumentation/#app-start-instrumentation">Cold and warm app start time</PlatformLink>.
+* <PlatformLink to="/performance/instrumentation/automatic-instrumentation/#slow-and-frozen-frames">Slow and frozen frame rendering</PlatformLink>.

src/platform-includes/performance/automatic-performance-metrics/apple.mdx

@@ -0,0 +1,4 @@
+If configured, the Cocoa SDK automatically collects the following performance metrics:
+
+* <PlatformLink to="/performance/instrumentation/automatic-instrumentation/#app-start-tracking">Cold and warm app start time</PlatformLink>
+* <PlatformLink to="/performance/instrumentation/automatic-instrumentation/#slow-and-frozen-frames">Slow and frozen frame rendering</PlatformLink>

src/platform-includes/performance/custom-performance-metrics/apple.mdx

@@ -0,0 +1,32 @@
+Adding custom metrics is supported in Sentry's Cocoa SDK, version `7.28.0` and above.
+
+```swift {tabTitle: Swift}
+import Sentry
+
+let span = SentrySDK.span;
+
+// Record amount of memory used
+span?.setMeasurement(name: "memory_used", value: 64, unit: MeasurementUnitInformation.megabyte);
+
+// Record time it took to load user profile
+span?.setMeasurement(name: "user_profile_loading_time", value: 1.3, unit: MeasurementUnitDuration.second);
+
+// Record number of times the screen was loaded
+span?.setMeasurement(name: "screen_load_count", value: 4);
+```
+
+```objc {tabTitle:Objective-C}
+@import Sentry;
+
+id<SentrySpan> span = SentrySDK.span;
+if (span != nil) {
+    // Record amount of memory used
+    [span setMeasurement:@"memory_used" value:@64 unit:SentryMeasurementUnitInformation.megabyte];
+
+    // Record time it took to load user profile
+    [span setMeasurement:@"user_profile_loading_time" value:@1.3 unit:SentryMeasurementUnitDuration.second];
+
+    // Record number of times the screen was loaded
+    [span setMeasurement:@"screen_load_count" value:@4];
+}
+```

src/platform-includes/performance/custom-performance-metrics/java.mdx

@@ -1,4 +1,4 @@
-Adding custom metrics is supported in Sentry's Java SDK version `6.5.0` and above.
+Adding custom metrics is supported in Sentry's Java SDK, version `6.5.0` and above.
 
 ```java {tabTitle:Java}
 import io.sentry.ISpan;

src/platforms/common/performance/instrumentation/performance-metrics.mdx

@@ -10,13 +10,13 @@ supported:
   - java
   - java.spring-boot
   - android
+  - apple
 notSupported:
   - javascript.cordova
   - javascript.electron
   - dotnet
   - go
   - ruby
-  - apple
   - unity
   - rust
   - native
@@ -31,7 +31,7 @@ description: "Learn how to attach performance metrics to your transactions."
 
 Sentry's SDKs support sending performance metrics data to Sentry. These are numeric values attached to transactions that are aggregated and displayed in Sentry.
 
-<PlatformSection supported={["javascript", "android"]} notSupported={["react-native"]}>
+<PlatformSection supported={["javascript", "android", "apple"]} notSupported={["react-native"]}>
 
 <PlatformContent includePath="performance/automatic-performance-metrics" />