iOS: fix compile-time warnings

[mortend]

This fixes some compile-time warnings when building for iOS.

/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:123:4: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:127:34: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:129:36: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:129:81: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:131:4: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:136:4: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:137:7: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:140:34: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:142:36: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:142:81: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:144:4: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:146:7: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:147:5: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:152:4: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:153:7: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:154:7: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:155:5: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:176:24: warning: initializing 'FusePinAnnotation *__strong' with an expression of incompatible type 'id<MKAnnotation> _Nullable'
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/MapViewDelegate.m:322:23: warning: initializing 'FusePinAnnotation *__strong' with an expression of incompatible type '__strong id<MKAnnotation> _Nonnull'
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/KeyboardContext.mm:30:100: warning: implicit conversion loses integer precision: 'UIViewAnimationCurve' to 'int32_t' (aka 'int') [-Wshorten-64-to-32]
/Users/morten/fuselibs/Tests/ManualTests/ManualTestingApp/build/iOS/Debug/src/iOS/ImagePicker.m:23:37: warning: block implicitly retains 'self'; explicitly mention 'self' to indicate this is intended behavior [-Wimplicit-retain-self]